Processing a write request in a dispersed storage network

ABSTRACT

A method begins by a processing module receiving a write request regarding an encoded data slice and determining whether the write request pertains to deleting the encoded data slice from a memory space. The method continues with the processing module storing a deletion marker regarding the encoded data slice when the write request pertains to deleting the encoded data slice. The method continues with the processing module determining when to delete the encoded data slice based on the deletion marker and in accordance with the deletion scheme.

CROSS REFERENCE TO RELATED PATENTS

This patent application is claiming priority under 35 USC §119 to aprovisionally filed patent application entitled DISPERSED STORAGENETWORK ACCESS REQUEST AUTHENTICATION, having a provisional filing dateof Aug. 02, 2010, and a provisional Ser. No. of 61/369,812, which isincorporated by reference in its entirety and made part of the presentU.S. Utility Patent Application for all purposes, and is furtherclaiming priority under 35 U.S.C. §120, as a continuation-in-part (CIP),to U.S. Utility Patent Application having a Ser. No. 12/838,407,entitled DISTRIBUTED STORAGE REVISION ROLLBACKS, and a filing date ofJul. 16, 2010, which claims priority under 35 USC §119 to aprovisionally filed patent application entitled DISTRIBUTED STORAGENETWORK DATA REVISION CONTROL, having a provisional filing date of Oct.29,2009, and a provisional Ser. No. of 61/256,226.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

NOT APPLICABLE

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

NOT APPLICABLE

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to computing systems and moreparticularly to data storage solutions within such computing systems.

2. Description of Related Art

Computers are known to communicate, process, and store data. Suchcomputers range from wireless smart phones to data centers that supportmillions of web searches, stock trades, or on-line purchases every day.In general, a computing system generates data and/or manipulates datafrom one form into another. For instance, an image sensor of thecomputing system generates raw picture data and, using an imagecompression program (e.g., JPEG, MPEG, etc.), the computing systemmanipulates the raw picture data into a standardized compressed image.

With continued advances in processing speed and communication speed,computers are capable of processing real time multimedia data forapplications ranging from simple voice communications to streaming highdefinition video. As such, general-purpose information appliances arereplacing purpose-built communications devices (e.g., a telephone). Forexample, smart phones can support telephony communications but they arealso capable of text messaging and accessing the internet to performfunctions including email, web browsing, remote applications access, andmedia communications (e.g., telephony voice, image transfer, musicfiles, video files, real time video streaming. etc.).

Each type of computer is constructed and operates in accordance with oneor more communication, processing, and storage standards. As a result ofstandardization and with advances in technology, more and moreinformation content is being converted into digital formats. Forexample, more digital cameras are now being sold than film cameras, thusproducing more digital pictures. As another example, web-basedprogramming is becoming an alternative to over the air televisionbroadcasts and/or cable broadcasts. As further examples, papers, books,video entertainment, home video, etc. are now being stored digitally,which increases the demand on the storage function of computers.

A typical computer storage system includes one or more memory devicesaligned with the needs of the various operational aspects of thecomputer's processing and communication functions. Generally, theimmediacy of access dictates what type of memory device is used. Forexample, random access memory (RAM) memory can be accessed in any randomorder with a constant response time, thus it is typically used for cachememory and main memory. By contrast, memory device technologies thatrequire physical movement such as magnetic disks, tapes, and opticaldiscs, have a variable response time as the physical movement can takelonger than the data transfer, thus they are typically used forsecondary memory (e.g., hard drive, backup memory, etc.).

A computer's storage system will be compliant with one or more computerstorage standards that include, but are not limited to, network filesystem (NFS), flash file system (FFS), disk file system (DFS), smallcomputer system interface (SCSI), internet small computer systeminterface (iSCSI), file transfer protocol (FTP), and web-baseddistributed authoring and versioning (WebDAV). These standards specifythe data storage format (e.g., files, data objects, data blocks,directories, etc.) and interfacing between the computer's processingfunction and its storage system, which is a primary function of thecomputer's memory controller.

Despite the standardization of the computer and its storage system,memory devices fail; especially commercial grade memory devices thatutilize technologies incorporating physical movement (e.g., a discdrive). For example, it is fairly common for a disc drive to routinelysuffer from bit level corruption and to completely fail after threeyears of use. One solution is to a higher-grade disc drive, which addssignificant cost to a computer.

Another solution is to utilize multiple levels of redundant disc drivesto replicate the data into two or more copies. One such redundant driveapproach is called redundant array of independent discs (RAID). In aRAID device, a RAID controller adds parity data to the original databefore storing it across the array. The parity data is calculated fromthe original data such that the failure of a disc will not result in theloss of the original data. For example, RAID 5 uses three discs toprotect data from the failure of a single disc. The parity data, andassociated redundancy overhead data, reduces the storage capacity ofthree independent discs by one third (e.g., n−1=capacity). RAID 6 canrecover from a loss of two discs and requires a minimum of four discswith a storage capacity of n−2.

While RAID addresses the memory device failure issue, it is not withoutits own failures issues that affect its effectiveness, efficiency andsecurity. For instance, as more discs are added to the array, theprobability of a disc failure increases, which increases the demand formaintenance. For example, when a disc fails, it needs to be manuallyreplaced before another disc fails and the data stored in the RAIDdevice is lost. To reduce the risk of data loss, data on a RAID deviceis typically copied on to one or more other RAID devices. While thisaddresses the loss of data issue, it raises a security issue sincemultiple copies of data are available, which increases the chances ofunauthorized access. Further, as the amount of data being stored grows,the overhead of RAID devices becomes a non-trivial efficiency issue.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a computingsystem in accordance with the invention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the invention;

FIG. 3 is a schematic block diagram of an embodiment of a distributedstorage processing unit in accordance with the invention;

FIG. 4 is a schematic block diagram of an embodiment of a grid module inaccordance with the invention;

FIG. 5 is a diagram of an example embodiment of error coded data slicecreation in accordance with the invention;

FIG. 6A is a flowchart illustrating an example of authenticating arequest in accordance with the invention;

FIG. 6B is a flowchart illustrating an example of refreshing a localauthentication list in accordance with the invention;

FIG. 7A is a diagram illustrating an example of an authenticationsequence bounce diagram in accordance with the invention;

FIG. 7B is a flowchart illustrating an example of authenticating a dataaccess request in accordance with the invention;

FIG. 7C is a flowchart illustrating an example of processing anauthentication request in accordance with the invention;

FIG. 8A is a flowchart illustrating an example of acquiring anauthentication token in accordance with the invention;

FIG. 8B is a flowchart illustrating an example of processing anauthentication token request in accordance with the invention;

FIG. 9 is a flowchart illustrating an example of processing a request inaccordance with the invention;

FIG. 10 is a flowchart illustrating an example of retrieving error codeddata slices in accordance with the invention;

FIG. 11 is a flowchart illustrating an example of processing a writerequest in accordance with the invention;

FIG. 12 is a flowchart illustrating an example of determining storagegeneration operational modes in accordance with the invention;

FIG. 13 is a flowchart illustrating an example of manipulating pre-slicedata in accordance with the invention;

FIG. 14 is a flowchart illustrating an example of error correcting adata slice in accordance with the invention;

FIG. 15A is a schematic block diagram of an embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 15B is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 15C is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 15D is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 16 is a flowchart illustrating an example of implementing a storagepolicy in accordance with the invention;

FIG. 17A is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 17B is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 17C is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network memory in accordance with theinvention;

FIG. 18 is a flowchart illustrating an example of expanding andcontracting storage resources in accordance with the invention;

FIG. 19 is a schematic block diagram of an embodiment of a communicationsystem in accordance with the invention;

FIG. 20 is a flowchart illustrating an example of acquiring a contentbroadcast in accordance with the invention;

FIG. 21 is a flowchart illustrating an example of generating a contentbroadcast in accordance with the invention;

FIG. 22 is a table illustrating an example of wireless configuration andpillar assignments in accordance with the invention;

FIG. 23 is a flowchart illustrating another example of acquiring acontent broadcast in accordance with the invention; and

FIG. 24 is a flowchart illustrating another example of acquiring acontent broadcast in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of a computing system 10 thatincludes one or more of a first type of user devices 12, one or more ofa second type of user devices 14, at least one distributed storage (DS)processing unit 16, at least one DS managing unit 18, at least onestorage integrity processing unit 20, and a distributed storage network(DSN) memory 22 coupled via a network 24. The network 24 may include oneor more wireless and/or wire lined communication systems; one or moreprivate intranet systems and/or public internet systems; and/or one ormore local area networks (LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of distributed storage (DS) units36 for storing data of the system. Each of the DS units 36 includes aprocessing module and memory and may be located at a geographicallydifferent site than the other DS units (e.g., one in Chicago, one inMilwaukee, etc.). The processing module may be a single processingdevice or a plurality of processing devices. Such a processing devicemay be a microprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on hard coding of the circuitry and/oroperational instructions. The processing module may have an associatedmemory and/or memory element, which may be a single memory device, aplurality of memory devices, and/or embedded circuitry of the processingmodule. Such a memory device may be a read-only memory, random accessmemory, volatile memory, non-volatile memory, static memory, dynamicmemory, flash memory, cache memory, and/or any device that storesdigital information. Note that if the processing module includes morethan one processing device, the processing devices may be centrallylocated (e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that when the processing module implements one or more ofits functions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory and/or memory element storing thecorresponding operational instructions may be embedded within, orexternal to, the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. Still further notethat, the memory element stores, and the processing module executes,hard coded and/or operational instructions corresponding to at leastsome of the steps and/or functions illustrated in FIGS. 1-24.

Each of the user devices 12-14, the DS processing unit 16, the DSmanaging unit 18, and the storage integrity processing unit 20 may be aportable computing device (e.g., a social networking device, a gamingdevice, a cell phone, a smart phone, a personal digital assistant, adigital music player, a digital video player, a laptop computer, ahandheld computer, a video game controller, and/or any other portabledevice that includes a computing core) and/or a fixed computing device(e.g., a personal computer, a computer server, a cable set-top box, asatellite receiver, a television set, a printer, a fax machine, homeentertainment equipment, a video game console, and/or any type of homeor office computing equipment). Such a portable or fixed computingdevice includes a computing core 26 and one or more interfaces 30, 32,and/or 33. An embodiment of the computing core 26 will be described withreference to FIG. 2.

With respect to the interfaces, each of the interfaces 30, 32, and 33includes software and/or hardware to support one or more communicationlinks via the network 24 and/or directly. For example, interfaces 30support a communication link (wired, wireless, direct, via a LAN, viathe network 24, etc.) between the first type of user device 14 and theDS processing unit 16. As another example, DSN interface 32 supports aplurality of communication links via the network 24 between the DSNmemory 22 and the DS processing unit 16, the first type of user device12, and/or the storage integrity processing unit 20. As yet anotherexample, interface 33 supports a communication link between the DSmanaging unit 18 and any one of the other devices and/or units 12, 14,16, 20, and/or 22 via the network 24.

In general and with respect to data storage, the system 10 supportsthree primary functions: distributed network data storage management,distributed data storage and retrieval, and data storage integrityverification. In accordance with these three primary functions, data canbe distributedly stored in a plurality of physically different locationsand subsequently retrieved in a reliable and secure manner regardless offailures of individual storage devices, failures of network equipment,the duration of storage, the amount of data being stored, attempts athacking the data, etc.

The DS managing unit 18 performs distributed network data storagemanagement functions, which include establishing distributed datastorage parameters, performing network operations, performing networkadministration, and/or performing network maintenance. The DS managingunit 18 establishes the distributed data storage parameters (e.g.,allocation of virtual DSN memory space, distributed storage parameters,security parameters, billing information, user profile information,etc.) for one or more of the user devices 12-14 (e.g., established forindividual devices, established for a user group of devices, establishedfor public access by the user devices, etc.). For example, the DSmanaging unit 18 coordinates the creation of a vault (e.g., a virtualmemory block) within the DSN memory 22 for a user device (for a group ofdevices, or for public access). The DS managing unit 18 also determinesthe distributed data storage parameters for the vault. In particular,the DS managing unit 18 determines a number of slices (e.g., the numberthat a data segment of a data file and/or data block is partitioned intofor distributed storage) and a read threshold value (e.g., the minimumnumber of slices required to reconstruct the data segment).

As another example, the DS managing module 18 creates and stores,locally or within the DSN memory 22, user profile information. The userprofile information includes one or more of authentication information,permissions, and/or the security parameters. The security parameters mayinclude one or more of encryption/decryption scheme, one or moreencryption keys, key generation scheme, and data encoding/decodingscheme.

As yet another example, the DS managing unit 18 creates billinginformation for a particular user, user group, vault access, publicvault access, etc. For instance, the DS managing unit 18 tracks thenumber of times user accesses a private vault and/or public vaults,which can be used to generate a per-access bill. In another instance,the DS managing unit 18 tracks the amount of data stored and/orretrieved by a user device and/or a user group, which can be used togenerate a per-data-amount bill.

The DS managing unit 18 also performs network operations, networkadministration, and/or network maintenance. As at least part ofperforming the network operations and/or administration, the DS managingunit 18 monitors performance of the devices and/or units of the system10 for potential failures, determines the devices and/or unit'sactivation status, determines the devices' and/or units' loading, andany other system level operation that affects the performance level ofthe system 10. For example, the DS managing unit 18 receives andaggregates network management alarms, alerts, errors, statusinformation, performance information, and messages from the devices12-14 and/or the units 16, 20, 22. For example, the DS managing unit 18receives a simple network management protocol (SNMP) message regardingthe status of the DS processing unit 16.

The DS managing unit 18 performs the network maintenance by identifyingequipment within the system 10 that needs replacing, upgrading,repairing, and/or expanding. For example, the DS managing unit 18determines that the DSN memory 22 needs more DS units 36 or that one ormore of the DS units 36 needs updating.

The second primary function (i.e., distributed data storage andretrieval) begins and ends with a user device 12-14. For instance, if asecond type of user device 14 has a data file 38 and/or data block 40 tostore in the DSN memory 22, it send the data file 38 and/or data block40 to the DS processing unit 16 via its interface 30. As will bedescribed in greater detail with reference to FIG. 2, the interface 30functions to mimic a conventional operating system (OS) file systeminterface (e.g., network file system (NFS), flash file system (FFS),disk file system (DFS), file transfer protocol (FTP), web-baseddistributed authoring and versioning (WebDAV), etc.) and/or a blockmemory interface (e.g., small computer system interface (SCSI), internetsmall computer system interface (iSCSI), etc.). In addition, theinterface 30 may attach a user identification code (ID) to the data file38 and/or data block 40.

The DS processing unit 16 receives the data file 38 and/or data block 40via its interface 30 and performs a distributed storage (DS) process 34thereon (e.g., an error coding dispersal storage function). The DSprocessing 34 begins by partitioning the data file 38 and/or data block40 into one or more data segments, which is represented as Y datasegments. For example, the DS processing 34 may partition the data file38 and/or data block 40 into a fixed byte size segment (e.g., 2¹ to2^(n) bytes, where n=>2) or a variable byte size (e.g., change byte sizefrom segment to segment, or from groups of segments to groups ofsegments, etc.).

For each of the Y data segments, the DS processing 34 error encodes(e.g., forward error correction (FEC), information dispersal algorithm,or error correction coding) and slices (or slices then error encodes)the data segment into a plurality of error coded (EC) data s2-48, whichis represented as X slices per data segment. The number of slices (X)per segment, which corresponds to a number of pillars n, is set inaccordance with the distributed data storage parameters and the errorcoding scheme. For example, if a Reed-Solomon (or other FEC scheme) isused in an n/k system, then a data segment is divided into n slices,where k number of slices is needed to reconstruct the original data(i.e., k is the threshold). As a few specific examples, the n/k factormay be 5/3; 6/4; 8/6; 8/5; 16/10.

For each s2-48, the DS processing unit 16 creates a unique slice nameand appends it to the corresponding s2-48. The slice name includesuniversal DSN memory addressing routing information (e.g., virtualmemory addresses in the DSN memory 22) and user-specific information(e.g., user ID, file name, data block identifier, etc.).

The DS processing unit 16 transmits the plurality of EC s2-48 to aplurality of DS units 36 of the DSN memory 22 via the DSN interface 32and the network 24. The DSN interface 32 formats each of the slices fortransmission via the network 24. For example, the DSN interface 32 mayutilize an internet protocol (e.g., TCP/IP, etc.) to packetize the s2-48for transmission via the network 24.

The number of DS units 36 receiving the s2-48 is dependent on thedistributed data storage parameters established by the DS managing unit18. For example, the DS managing unit 18 may indicate that each slice isto be stored in a different DS unit 36. As another example, the DSmanaging unit 18 may indicate that like slice numbers of different datasegments are to be stored in the same DS unit 36. For example, the firstslice of each of the data segments is to be stored in a first DS unit36, the second slice of each of the data segments is to be stored in asecond DS unit 36, etc. In this manner, the data is encoded anddistributedly stored at physically diverse locations to improved datastorage integrity and security. Further examples of encoding the datasegments will be provided with reference to one or more of FIGS. 2-24.

Each DS unit 36 that receives a s2-48 for storage translates the virtualDSN memory address of the slice into a local physical address forstorage. Accordingly, each DS unit 36 maintains a virtual to physicalmemory mapping to assist in the storage and retrieval of data.

The first type of user device 12 performs a similar function to storedata in the DSN memory 22 with the exception that it includes the DSprocessing. As such, the device 12 encodes and slices the data fileand/or data block it has to store. The device then transmits the s1 tothe DSN memory via its DSN interface 32 and the network 24.

For a second type of user device 14 to retrieve a data file or datablock from memory, it issues a read command via its interface 30 to theDS processing unit 16. The DS processing unit 16 performs the DSprocessing 34 to identify the DS units 36 storing the slices of the datafile and/or data block based on the read command. The DS processing unit16 may also communicate with the DS managing unit 18 to verify that theuser device 14 is authorized to access the requested data.

Assuming that the user device is authorized to access the requesteddata, the DS processing unit 16 issues slice read commands to at least athreshold number of the DS units 36 storing the requested data (e.g., toat least 10 DS units for a 16/10 error coding scheme). Each of the DSunits 36 receiving the slice read command, verifies the command,accesses its virtual to physical memory mapping, retrieves the requestedslice, or slices, and transmits it to the DS processing unit 16.

Once the DS processing unit 16 has received a read threshold number ofslices for a data segment, it performs an error decoding function andde-slicing to reconstruct the data segment. When Y number of datasegments has been reconstructed, the DS processing unit 16 provides thedata file 38 and/or data block 40 to the user device 14. Note that thefirst type of user device 12 performs a similar process to retrieve adata file and/or data block.

The storage integrity processing unit 20 performs the third primaryfunction of data storage integrity verification. In general, the storageintegrity processing unit 20 periodically retrieves s5, and/or slicenames, of a data file or data block of a user device to verify that oneor more slices have not been corrupted or lost (e.g., the DS unitfailed). The retrieval process mimics the read process previouslydescribed.

If the storage integrity processing unit 20 determines that one or moreslices is corrupted or lost, it rebuilds the corrupted or lost slice(s)in accordance with the error coding scheme. The storage integrityprocessing unit 20 stores the rebuild slice, or slices, in theappropriate DS unit(s) 36 in a manner that mimics the write processpreviously described.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,at least one IO device interface module 62, a read only memory (ROM)basic input output system (BIOS) 64, and one or more memory interfacemodules. The memory interface module(s) includes one or more of auniversal serial bus (USB) interface module 66, a host bus adapter (HBA)interface module 68, a network interface module 70, a flash interfacemodule 72, a hard drive interface module 74, and a DSN interface module76. Note the DSN interface module 76 and/or the network interface module70 may function as the interface 30 of the user device 14 of FIG. 1.Further note that the IO device interface module 62 and/or the memoryinterface modules may be collectively or individually referred to as IOports.

The processing module 50 may be a single processing device or aplurality of processing devices. Such a processing device may be amicroprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on hard coding of the circuitry and/oroperational instructions. The processing module 50 may have anassociated memory and/or memory element, which may be a single memorydevice, a plurality of memory devices, and/or embedded circuitry of theprocessing module 50. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module 50includes more than one processing device, the processing devices may becentrally located (e.g., directly coupled together via a wired and/orwireless bus structure) or may be distributedly located (e.g., cloudcomputing via indirect coupling via a local area network and/or a widearea network). Further note that when the processing module 50implements one or more of its functions via a state machine, analogcircuitry, digital circuitry, and/or logic circuitry, the memory and/ormemory element storing the corresponding operational instructions may beembedded within, or external to, the circuitry comprising the statemachine, analog circuitry, digital circuitry, and/or logic circuitry.Still further note that, the memory element stores, and the processingmodule 50 executes, hard coded and/or operational instructionscorresponding to at least some of the steps and/or functions illustratedin FIGS. 1-24.

FIG. 3 is a schematic block diagram of an embodiment of a dispersedstorage (DS) processing module 34 of user device 12 and/or of the DSprocessing unit 16. The DS processing module 34 includes a gatewaymodule 78, an access module 80, a grid module 82, and a storage module84. The DS processing module 34 may also include an interface 30 and theDSnet interface 32 or the interfaces 68 and/or 70 may be part of user 12or of the DS processing unit 14. The DS processing module 34 may furtherinclude a bypass/feedback path between the storage module 84 to thegateway module 78. Note that the modules 78-84 of the DS processingmodule 34 may be in a single unit or distributed across multiple units.

In an example of storing data, the gateway module 78 receives anincoming data object that includes a user ID field 86, an object namefield 88, and the data field 40 and may also receive correspondinginformation that includes a process identifier (e.g., an internalprocess/application ID), metadata, a file system directory, a blocknumber, a transaction message, a user device identity (ID), a dataobject identifier, a source name, and/or user information. The gatewaymodule 78 authenticates the user associated with the data object byverifying the user ID 86 with the managing unit 18 and/or anotherauthenticating unit.

When the user is authenticated, the gateway module 78 obtains userinformation from the management unit 18, the user device, and/or theother authenticating unit. The user information includes a vaultidentifier, operational parameters, and user attributes (e.g., userdata, billing information, etc.). A vault identifier identifies a vault,which is a virtual memory space that maps to a set of DS storage units36. For example, vault 1 (i.e., user 1's DSN memory space) includeseight DS storage units (X=8 wide) and vault 2 (i.e., user 2's DSN memoryspace) includes sixteen DS storage units (X=16 wide). The operationalparameters may include an error coding algorithm, the width n (number ofpillars X or slices per segment for this vault), a read threshold T, awrite threshold, an encryption algorithm, a slicing parameter, acompression algorithm, an integrity check method, caching settings,parallelism settings, and/or other parameters that may be used to accessthe DSN memory layer.

The gateway module 78 uses the user information to assign a source name35 to the data. For instance, the gateway module 60 determines thesource name 35 of the data object 40 based on the vault identifier andthe data object. For example, the source name may contain a fileidentifier (ID), a vault generation number, a reserved field, and avault identifier (ID). As another example, the gateway module 78 maygenerate the file ID based on a hash function of the data object 40.Note that the gateway module 78 may also perform message conversion,protocol conversion, electrical conversion, optical conversion, accesscontrol, user identification, user information retrieval, trafficmonitoring, statistics generation, configuration, management, and/orsource name determination.

The access module 80 receives the data object 40 and creates a series ofdata segments 1 through Y 90-92 in accordance with a data storageprotocol (e.g., file storage system, a block storage system, and/or anaggregated block storage system). The number of segments Y may be chosenor randomly assigned based on a selected segment size and the size ofthe data object. For example, if the number of segments is chosen to bea fixed number, then the size of the segments varies as a function ofthe size of the data object. For instance, if the data object is animage file of 4,194,304 eight bit bytes (e.g., 33,554,432 bits) and thenumber of segments Y=131,072, then each segment is 256 bits or 32 bytes.As another example, if segment sized is fixed, then the number ofsegments Y varies based on the size of data object. For instance, if thedata object is an image file of 4,194,304 bytes and the fixed size ofeach segment is 4,096 bytes, the then number of segments Y=1,024. Notethat each segment is associated with the same source name.

The grid module 82 receives the data segments and may manipulate (e.g.,compression, encryption, cyclic redundancy check (CRC), etc.) each ofthe data segments before performing an error coding function of theerror coding dispersal storage function to produce a pre-manipulateddata segment. After manipulating a data segment, if applicable, the gridmodule 82 error encodes (e.g., Reed-Solomon, Convolution encoding,Trellis encoding, etc.) the data segment or manipulated data segmentinto X error coded data s2-44.

The value X, or the number of pillars (e.g., X=16), is chosen as aparameter of the error coding dispersal storage function. Otherparameters of the error coding dispersal function include a readthreshold T, a write threshold W, etc. The read threshold (e.g., T=10,when X=16) corresponds to the minimum number of error-free error codeddata slices required to reconstruct the data segment. In other words,the DS processing module 34 can compensate for X-T (e.g., 16−10=6)missing error coded data slices per data segment. The write threshold Wcorresponds to a minimum number of DS storage units that acknowledgeproper storage of their respective data slices before the DS processingmodule indicates proper storage of the encoded data segment. Note thatthe write threshold is greater than or equal to the read threshold for agiven number of pillars (X).

For each data slice of a data segment, the grid module 82 generates aunique slice name 37 and attaches it thereto. The slice name 37 includesa universal routing information field and a vault specific field and maybe 48 bytes (e.g., 24 bytes for each of the universal routinginformation field and the vault specific field). As illustrated, theuniversal routing information field includes a slice index, a vault ID,a vault generation, and a reserved field. The slice index is based onthe pillar number and the vault ID and, as such, is unique for eachpillar (e.g., slices of the same pillar for the same vault for anysegment will share the same slice index). The vault specific fieldincludes a data name, which includes a file ID and a segment number(e.g., a sequential numbering of data segments 1-Y of a simple dataobject or a data block number).

Prior to outputting the error coded data slices of a data segment, thegrid module may perform post-slice manipulation on the slices. Ifenabled, the manipulation includes slice level compression, encryption,CRC, addressing, tagging, and/or other manipulation to improve theeffectiveness of the computing system.

When the error coded data slices of a data segment are ready to beoutputted, the grid module 82 determines which of the DS storage units36 will store the EC data slices based on a dispersed storage memorymapping associated with the user's vault and/or DS storage unitattributes. The DS storage unit attributes may include availability,self-selection, performance history, link speed, link latency,ownership, available DSN memory, domain, cost, a prioritization scheme,a centralized selection message from another source, a lookup table,data ownership, and/or any other factor to optimize the operation of thecomputing system. Note that the number of DS storage units 36 is equalto or greater than the number of pillars (e.g., X) so that no more thanone error coded data slice of the same data segment is stored on thesame DS storage unit 36. Further note that EC data slices of the samepillar number but of different segments (e.g., EC data slice 1 of datasegment 1 and EC data slice 1 of data segment 2) may be stored on thesame or different DS storage units 36.

The storage module 84 performs an integrity check on the outboundencoded data slices and, when successful, identifies a plurality of DSstorage units based on information provided by the grid module 82. Thestorage module 84 then outputs the encoded data slices 1 through X ofeach segment 1 through Y to the DS storage units 36. Each of the DSstorage units 36 stores its EC data slice(s) and maintains a localvirtual DSN address to physical location table to convert the virtualDSN address of the EC data slice(s) into physical storage addresses.

In an example of a read operation, the user device 12 and/or 14 sends aread request to the DS processing unit 14, which authenticates therequest. When the request is authentic, the DS processing unit 14 sendsa read message to each of the DS storage units 36 storing slices of thedata object being read. The slices are received via the DSnet interface32 and processed by the storage module 84, which performs a parity checkand provides the slices to the grid module 82 when the parity check wassuccessful. The grid module 82 decodes the slices in accordance with theerror coding dispersal storage function to reconstruct the data segment.The access module 80 reconstructs the data object from the data segmentsand the gateway module 78 formats the data object for transmission tothe user device.

FIG. 4 is a schematic block diagram of an embodiment of a grid module 82that includes a control unit 73, a pre-slice manipulator 75, an encoder77, a slicer 79, a post-slice manipulator 81, a pre-slice de-manipulator83, a decoder 85, a de-slicer 87, and/or a post-slice de-manipulator 89.Note that the control unit 73 may be partially or completely external tothe grid module 82. For example, the control unit 73 may be part of thecomputing core at a remote location, part of a user device, part of theDS managing unit 18, or distributed amongst one or more DS storageunits.

In an example of write operation, the pre-slice manipulator 75 receivesa data segment 90-92 and a write instruction from an authorized userdevice. The pre-slice manipulator 75 determines if pre-manipulation ofthe data segment 90-92 is required and, if so, what type. The pre-slicemanipulator 75 may make the determination independently or based oninstructions from the control unit 73, where the determination is basedon a computing system-wide predetermination, a table lookup, vaultparameters associated with the user identification, the type of data,security requirements, available DSN memory, performance requirements,and/or other metadata.

Once a positive determination is made, the pre-slice manipulator 75manipulates the data segment 90-92 in accordance with the type ofmanipulation. For example, the type of manipulation may be compression(e.g., Lempel-Ziv-Welch, Huffman, Golomb, fractal, wavelet, etc.),signatures (e.g., Digital Signature Algorithm (DSA), Elliptic Curve DSA,Secure Hash Algorithm, etc.), watermarking, tagging, encryption (e.g.,Data Encryption Standard, Advanced Encryption Standard, etc.), addingmetadata (e.g., time/date stamping, user information, file type, etc.),cyclic redundancy check (e.g., CRC32), and/or other data manipulationsto produce the pre-manipulated data segment.

The encoder 77 encodes the pre-manipulated data segment 92 using aforward error correction (FEC) encoder (and/or other type of erasurecoding and/or error coding) to produce an encoded data segment 94. Theencoder 77 determines which forward error correction algorithm to usebased on a predetermination associated with the user's vault, a timebased algorithm, user direction, DS managing unit direction, controlunit direction, as a function of the data type, as a function of thedata segment 92 metadata, and/or any other factor to determine algorithmtype. The forward error correction algorithm may be Golay,Multidimensional parity, Reed-Solomon, Hamming, Bose Ray ChauduriHocquenghem (BCH), Cauchy-Reed-Solomon, or any other FEC encoder. Notethat the encoder 77 may use a different encoding algorithm for each datasegment 92, the same encoding algorithm for the data segments 92 of adata object, or a combination thereof.

The encoded data segment 94 is of greater size than the data segment 92by the overhead rate of the encoding algorithm by a factor of X/T, whereX is the width or number of slices, and T is the read threshold. In thisregard, the corresponding decoding process can accommodate at most X-Tmissing EC data slices and still recreate the data segment 92. Forexample, if X=16 and T=10, then the data segment 92 will be recoverableas long as 10 or more EC data slices per segment are not corrupted.

The slicer 79 transforms the encoded data segment 94 into EC data slicesin accordance with the slicing parameter from the vault for this userand/or data segment 92. For example, if the slicing parameter is X=16,then the slicer 79 slices each encoded data segment 94 into 16 encodedslices.

The post-slice manipulator 81 performs, if enabled, post-manipulation onthe encoded slices to produce the EC data slices. If enabled, thepost-slice manipulator 81 determines the type of post-manipulation,which may be based on a computing system-wide predetermination,parameters in the vault for this user, a table lookup, the useridentification, the type of data, security requirements, available DSNmemory, performance requirements, control unit directed, and/or othermetadata. Note that the type of post-slice manipulation may includeslice level compression, signatures, encryption, CRC, addressing,watermarking, tagging, adding metadata, and/or other manipulation toimprove the effectiveness of the computing system.

In an example of a read operation, the post-slice de-manipulator 89receives at least a read threshold number of EC data slices and performsthe inverse function of the post-slice manipulator 81 to produce aplurality of encoded slices. The de-slicer 87 de-slices the encodedslices to produce an encoded data segment 94. The decoder 85 performsthe inverse function of the encoder 77 to recapture the data segment90-92. The pre-slice de-manipulator 83 performs the inverse function ofthe pre-slice manipulator 75 to recapture the data segment 90-92.

FIG. 5 is a diagram of an example of slicing an encoded data segment 94by the slicer 79. In this example, the encoded data segment 94 includesthirty-two bits, but may include more or less bits. The slicer 79disperses the bits of the encoded data segment 94 across the EC dataslices in a pattern as shown. As such, each EC data slice does notinclude consecutive bits of the data segment 94 reducing the impact ofconsecutive bit failures on data recovery. For example, if EC data slice2 (which includes bits 1, 5, 9, 13, 17, 25, and 29) is unavailable(e.g., lost, inaccessible, or corrupted), the data segment can bereconstructed from the other EC data slices (e.g., 1, 3 and 4 for a readthreshold of 3 and a width of 4).

FIG. 6A is a flowchart illustrating an example of authenticating arequest. The method begins with step 102 where a processing module(e.g., of a dispersed storage (DS) processing unit) receives acredential from a requester (e.g., a user device). The method continuesat step 104 where the processing module determines whether thecredential matches an approved credential from a local authenticationlist. The determination may be based on whether the credential matchesan approved credential in the local authentication list and whether thecredential in the local authentication list has not expired (e.g., froma time perspective). The local authentication list includes one or morepreviously approved credentials (e.g., received from an authenticationauthority) and an associated one or more timestamps such that atimestamp is paired with each approved credential. The timestampindicates at least one of how long the credential is approved and whenthe credential expires. For example, the processing module determinesthat the credential is approved when the credential matches at least oneof the one or more previously approved credentials and the at least oneof the one or more previously approved credentials has not expired. Themethod branches to step 108 when the processing module determines thatthe credential does not match the approved credential in the localauthentication list. The method continues to step 106 when theprocessing module determines that the credential matches the approvedcredential in the local authentication list. The method continues atstep 106 where the processing module executes an associated request.

The method continues at step 108 where the processing module determineswhether the credential matches an approved credential in a remoteauthentication list (e.g., a list of the authentication authority). Forexample, the processing module sends an authentication request messageto the authentication authority that includes the credential. Theprocessing module receives an authentication response message thatindicates whether the credential matches an approved credential in theremote authentication list. The processing module determines that thecredential is approved when the authentication response message includesan indication that the credential matches an approved credential in theremote authentication list. The method branches to step 112 when theprocessing module determines that the credential matches the approvedcredential in the remote authentication list. The method continues tostep 110 when the processing module determines that the credential doesnot match the approved credential and the remote authentication list.The method continues at step 110 where the processing module rejects theassociated request when the processing module determines that thecredential is not approved. For example, the processing module sends areject message to the requester to reject the associated request.Alternatively, the processing module may execute the method as discussedin FIG. 6B when the processing module does not receive theauthentication response message in a timely manner (e.g., unable toaccess the remote authentication list).

The method continues at step 112 where the processing module creates atime stamped approved credential in the local authentication list whenthe processing module determines that the credential matches theapproved credential in the remote authentication list. For example, theprocessing module stores the credential and an associated expirationtimestamp in the local authentication list. The method continues at step114 where the processing module executes the associated request.

FIG. 6B is a flowchart illustrating an example of refreshing a localauthentication list. The method begins with step 116 where a processingmodule (e.g., of a dispersed storage (DS) processing unit) identifies anexpired approved credential in a local authentication list. Theidentification may be based on comparing an expiration timestampassociated with the approved credential to a current time. For example,the processing module determines that the approved credential is expiredwhen the current time is greater than the expiration timestamp. Themethod continues at step 118 where the processing module determineswhether a remote authentication list is accessible. The determinationmay be based on whether an authorization authority containing the remoteauthentication list is accessible (e.g., online). For example, theprocessing module determines that the remote authentication list isaccessible when the processing module receives an accessibility responsemessage from the authorization authority in response to receiving anaccessibility inquiry message from the processing module. The methodbranches to step 122 when the processing module determines that theremote authentication list is not accessible. The method continues tostep 120 when the processing module determines that the remoteauthentication list is accessible. The method continues at step 120where the processing module deletes the expired approved credential fromthe local authentication list. The method continues at step 122 wherethe processing module converts the expired approved credential to anactive approved credential when the processing module determines thatthe remote authentication list is not accessible. For example, theprocessing module extends the expiration timestamp associated with theexpired approved credential to convert the expired approved credentialto an active approved credential. In an instance, the processing moduleextends the expiration timestamp by one day.

FIG. 7A is a diagram illustrating an example of an authenticationsequence bounce diagram between a user device 12, a dispersed storage(DS) unit 36, and a DS managing unit 18. The sequence begins with a dataaccessing module (e.g., user device 12) of a dispersed storage network(DSN) sending a data access request 124 to a data storage module (e.g.,DS unit 36, DS processing unit 16) of the DSN. Alternatively, or inaddition to, the data accessing module sends a set of data accessrequests 124 to a set of data storage modules of the DSN. A data accessrequest includes one or more of a read request, a write request, a listrequest, a delete request, and an edit request. The sequence continueswhere the data storage module identifies an authenticating module (e.g.,DS managing unit 18) of the DSN for the data accessing module based onthe data access request. For example, the data storage module extracts auser device identifier (ID) from the data access request and utilizesthe user device ID in an authenticating module table lookup. Thesequence continues where the data storage module sends an authenticationrequest 126 to the authenticating module, wherein the authenticationrequest 126 includes at least a portion of the data access request. Forexample, the authentication request includes the user device ID, arequest type, and a data ID.

The sequence continues where the authenticating module outputs averification request 128 destined for the data accessing module, whereinthe verification request 128 includes a verification code that isgenerated based on the authentication request. A verification code maybe unique for the data access request and user ID and may include one ormore of a random number, a random string of characters, a nonce, asequential number, and a number based on a table lookup. The outputtingof the verification request by the authentication module includessending the verification request to the data storage module andforwarding, by the data storage module, the verification request to thedata accessing module.

The sequence continues where the data accessing module outputs averification response 130 destined for the authenticating module,wherein the verification response 130 includes a modified verificationcode that is generated based on the verification code and a credential.The credential includes at least one of a locally stored password, aremotely retrieved stored password, a password from a user input, a key,and an authenticator. The generating of the modified verification codeincludes one or more of performing a verifying function (e.g., adeterministic function, a hashing function, encryption, othermathematical manipulation) on the verification code and the credentialto produce the modified verification code; generating a second randomstring of characters; obtaining a certificate chain; generating asignature over the second random string of characters and theverification request; and obtaining a signature algorithm indicator. Thesignature is generated utilizing a private key associated with the dataaccessing module. The outputting of the verification response 130 by thedata accessing module includes sending the verification response 130 tothe data storage module and forwarding, by the data storage module, theverification response 130 to the authenticating module.

The sequence continues where the authenticating module outputs anauthentication response 132 to the data storage module, wherein theauthentication response 132 is generated based on the verificationresponse 130. The generating of the authentication response 132 includesperforming the verifying function on the verification code and areference credential to produce a reference verification code, comparingthe modified verification code with the reference verification code, andwhen the comparison is favorable, generating the authentication response132 to indicate a favorable authentication. A reference credentialincludes a stored credential. Alternatively, the generating of theauthentication response 132 includes verifying the signature of theverification response 130, utilizing a public key associated with thedata accessing module, and when the verifying is favorable, generatingthe authentication response 132 to indicate a favorable authentication.

The sequence continues where the data storage module facilitates thedata access request when the authentication response 132 is favorable.The facilitation may include outputting a data access response 134 tothe data accessing module. For example, the data storage module outputsa data access response 134 that includes an encoded data slice thatcorresponds to a slice name when the data access request 124 includes aread request for the slice name. The method of operation of the datastorage module and the authenticating module is discussed in greaterdetail of reference to FIGS. 7B and 7C.

FIG. 7B is a flowchart illustrating an example of authenticating a dataaccess request. The method begins with step 136 where a processingmodule (e.g., of a storage module) receives a data access request from adata accessing module of a dispersed storage network (DSN). The methodcontinues at step 138 where the processing module identifies anauthenticating module for the data accessing module based on the dataaccess request. The method continues at step 140 where the processingmodule sends an authentication request to the authenticating module ofthe DSN, wherein the authentication request includes at least a portionof the data access request. The method continues at step 142 where theprocessing module receives an authentication response from theauthenticating module, wherein the authentication response is generatedbased on a verification response of the data accessing module. Themethod continues at step 144 with a processing module facilitates thedata access request when the authentication response is favorable.

FIG. 7C is a flowchart illustrating an example of processing anauthentication request. The method begins with step 146 where aprocessing module (e.g., of an authenticating module) receives anauthentication request from a data storage module of a dispersed storagenetwork (DSN), wherein the authentication request includes at least aportion of a data access request of a data accessing module of the DSN.The method continues at step 148 where the processing module outputs averification request destined for the data accessing module, wherein theverification request includes a verification code that is generatedbased on the authentication request. The method continues at step 150where the processing module receives a verification response, whereinthe verification response includes a modified verification code that isgenerated by the data accessing module based on the verification codeand a credential. The method continues at step 152 where the processingmodule outputs an authentication response that is generated based on theverification response, wherein, the data access request is authenticatedwhen the authentication response is favorable. The generating theauthentication response includes performing a verifying function on theverification code and a reference credential to produce a referenceverification code, comparing the modified verification code with thereference verification code, and when the comparison is favorable,generating the authentication response to indicate a favorableauthentication.

FIG. 8A is a flowchart illustrating an example of acquiring anauthentication token. The method begins at step 154 where a processingmodule (e.g., a user device) generates and sends an authentication tokenrequest message that includes a credential. The credential includes oneor more of a user device identifier (ID), a password, a hash of thepassword, and a signature. For example, the processing module of a userdevice sends the request to an authentication authority (e.g., a DSmanaging unit). The authentication authority receives the authenticationtoken request message and generates an authentication token responsemessage in response. The method of operation of the authenticationauthority is discussed in greater detail with reference to FIG. 8B. Themethod continues at step 156 where the processing module receives theauthentication token response message. The authentication token responsemessage includes an authentication token, wherein the token includes oneor more of a permission, a timestamp associated with the permission, anda signature signed by the authentication authority.

The method continues at step 158 where the processing module generates adispersed storage network (DSN) access request. The generation may bebased on one or more of a user input, an application output, a readsequence, a write sequence, an access requirement, and a transferrequirement. For example, the processing module executes a storagesequence of a data object by generating a write request as the DSNaccess request. The method continues at step 160 where the processingmodule determines whether the authentication token is applicable to therequest. The processing module determines that the authentication tokenis applicable to the request when the request is allowable based onpermissions associated with the authentication token. For example, theprocessing module determines that the authentication token is applicableto the request when the request is a write request and a permissionallows the processing module to perform an associated write sequence(e.g., for a particular vault). The method repeats back to step 154 whenthe processing module determines that the authentication token is notapplicable. The method continues to step 162 when the processing moduledetermines that the authentication token is applicable.

The method continues at step 162 where the processing module sends arequest message that includes the DSN access request and theauthentication token. For example, the processing module sends therequest message to a dispersed storage (DS) unit to write an encodeddata slice to the DS unit. The method of operation to process therequest message is discussed in greater detail with reference to FIG. 9.

FIG. 8B is a flowchart illustrating an example of processing anauthentication token request. The method begins with step 164 where aprocessing module (e.g., of an authentication authority) receives anauthentication token request message that includes a credential. Forexample, the processing module receives the authentication token requestfrom a user device. The method continues at step 166 where theprocessing module verifies the credential (e.g., comparing a decryptedsignature to a hash of the request message). At step 166, the processingmodule determines whether the credential is valid based on comparing anelement of the credential to a stored representation of the credential.For example the processing module determines that the credential isvalid when a comparison of a password of the credential to a storedpassword associated with an identification of a user device indicatesthat the password and the stored password are substantially the same.The method branches to step 170 when the processing module determinesthat the credential is valid. The processing module continues to step168 when the processing module determines that the credential is notvalid. The method continues at step 168 where the processing modulerejects the authentication token request when the processing moduledetermines that the credential is not valid. For example, the processingmodule rejects the authentication token request by sending anauthentication token reject response message to the user device.

The method continues at step 170 where the processing module determinespermissions based on one or more of information contained in theauthentication token request message, a query, a lookup,predetermination, a message, and a command. For example, the processingmodule determines the permissions by a lookup into a permissions tableassociated with a user device identifier (ID) included in theauthentication token request message. The method continues at step 172where the processing module determines a token expiration. Thedetermination may be based on one or more of a requester identification,a predetermined time, a time associated with the requesteridentification, a request type, a message, and a command. The methodcontinues at step 174 where the processing module generates a signaturefor the authentication token. For example, the processing modulegenerates an encrypted hash of the permissions and token expiration (andany other elements of the authentication token) utilizing a private keyassociated with the processing module. The method continues at step 176where the processing module generates an authentication token byaggregating the permissions, the token expiration, and the signature.The method continues at step 178 where the processing module sends theauthentication token (e.g., to the user device).

FIG. 9 is a flowchart illustrating an example of processing a requestmessage. The method begins with step 180 where a processing module(e.g., of a dispersed storage (DS) unit) receives a request message thatincludes an authentication token. The method continues at step 182 wherethe processing module determines whether a signature associated with theauthentication token is valid (e.g., indicating valid when a comparisonof a decrypted signature to a hash of the authentication token indicatesthat they are substantially the same). The method branches to step 186when the processing module determines that the signature is valid. Themethod continues to step 184 when the processing module determines thatthe signature is not valid. The method continues at step 184 where theprocessing module rejects the request message when the processing moduledetermines that the signature is not valid. For example, the processingmodule sends a reject response message to a requester associated withthe request.

The method continues at step 186 where the processing module determinesvalid permissions based on permissions included in the authenticationtoken. The method continues at step 188 where the processing moduledetermines whether the valid permissions are applicable to the request.For example, the processing module determines that the valid permissionsare applicable when the valid permissions substantially encompasses therequest. For instance, the processing module determines that the validpermissions are applicable when the valid permissions allow a readrequest to access vault 100 for a user device identifier (ID) 356 andthe request is from user device ID 356 to read data from vault 100.

The method branches to step 192 when the processing module determinesthat the valid permissions are applicable. The method continues to step190 when the processing module determines that the valid permissions arenot applicable. The method continues at step 190 where the processingmodule rejects the request message when the processing module determinesthat the valid permissions are not applicable. For example, theprocessing module sends the reject response message to the requester anda DS managing unit. The method continues at step 192 where theprocessing module executes a request of the request message inaccordance with the valid permissions when the processing moduledetermines that the valid permissions are applicable. For example, theprocessing module accesses vault 100 for device ID 356.

FIG. 10 is a flowchart illustrating an example of retrieving error codeddata slices. The method begins with step 194 where a processing module(e.g., of a dispersed storage (DS) processing module) determines a datasegment to retrieve. The determination may be based on one or more of anaccess request, a data object name, a source name, a data segmentidentifier, a list, a query, a message, and a command. For example, theprocessing module receives a data object retrieval request message anddetermines the data segment to retrieve based on converting a dataobject name of the data object into a source name of the data object.The method continues at step 196 where the processing module determinesDS units to retrieve slices based on one or more of the data segmentidentifier, the source name, a slice name, and a virtual dispersedstorage network (DSN) address to physical location table lookup.

The method continues at step 198 where the processing module determinesperformance parameters. The performance parameters may include one ormore of input port bandwidth limitations, link speeds, a current averageinput port loading, DS unit performance history, a number of DS units,error coding dispersal storage function parameters, and retrievalsequences in progress. For example, the processing module determines theperformance parameters to include a 100 Mb per second input portbandwidth limitation and a current average input port loading of 60 Mbper second.

The method continues at step 200 where the processing module determinesa retrieval method based on one or more of the performance parameters, aperformance threshold, a number of DS units, a priority indicator, aperformance indicator, a security indicator, a command, and a message.The retrieval method includes sequencing the sending of retrievalmessages to the DS units in a timed pattern such that the average inputport loading is less than the input port bandwidth limitation. Forexample, processing module spaces the retrievals in time to avoidexceeding an input port bandwidth limitation.

The method continues at step 202 where the processing module sendsretrieval messages in accordance with the retrieval method. Theprocessing module may change the retrieval method based on updatedperformance parameters during the sending of the retrieval messages. Themethod continues at step 204 where the processing module receives errorcoded data slices from the DS units. The processing module may updatethe performance parameters based on performance of receiving of theerror coded data slices. The method continues at step 206 where theprocessing module decodes the error coded data slices in accordance withan error coding dispersal storage function to produce the data segment.

FIG. 11 is a flowchart illustrating an example of processing a writerequest. The method begins with step 208 where a processing module(e.g., of a dispersed storage (DS) unit) receives a write requestregarding an encoded data slice. The write request includes one or moreof a write request opcode, a slice name, an encoded data slice, and aslice length. The method continues at step 210 where the processingmodule determines whether the write request pertains to deleting theencoded data slice from a memory space (e.g., a memory space of a memoryassociated with the processing module). The determining whether thewrite request pertains to deleting the encoded data slice includesinterpreting the slice length field of the write request, indicatingthat the write request pertains to deleting the encoded data slice whenthe slice length field includes a first value, and indicating that thewrite request does not pertain to deleting the encoded data slice whenthe slice length field includes a second value. Such a value includes atleast one of a number, a delete flag, and a delete code. For example, afirst value includes a number zero and a second value includes anon-zero number. The method branches to step 218 when the processingmodule determines that the write request does not pertain to deletingthe encoded data slice. The method continues to step 212 when theprocessing module determines that the write request pertains to deletingthe encoded data slice.

The method continues at step 212 where the processing module stores adeletion marker regarding the encoded data slice when the write requestpertains to deleting the encoded data slice. For example, the processingmodule stores the deletion marker in a local directory. The methodcontinues at step 214 where the processing module determines when todelete the encoded data slice based on the deletion marker and inaccordance with a deletion scheme. The determining when to delete theencoded data slice includes at least one of deleting the encoded dataslice when memory availability compares unfavorably to a memoryavailability threshold, deleting the encoded data slice when apredetermined period of time has expired after receiving the writerequest, deleting the encoded data slice when utilization of the memoryspace compares unfavorably to a memory space usage threshold, anddeleting the encoded data slice based on a deletion instruction of thewrite request (e.g., receiving an instruction to immediately delete).

The memory availability includes a number of available bytes of a memoryassociated with the processing module (e.g., of a DS unit). For example,the processing module determines that memory availability comparesunfavorably to the memory availability threshold when memoryavailability is less than the memory availability threshold. Theutilization of the memory space includes a number of utilized bytes of amemory associated with one of the processing module (e.g., of a DS unit)and a vault (e.g., associated with one or more user devices such as avault). For example, the processing module determines that utilizationof the memory space compares unfavorably to the memory space usagethreshold when utilization of the memory space is greater than thememory space usage threshold. The method loops back to step 214 when theprocessing module determines not to delete the encoded data slice. Themethod continues to step 216 one the processing module determines todelete the encoded data slice. The method continues at step 216 wherethe processing module deletes the encoded data slice. For example, theprocessing module deletes the encoded data slice from the memory anddeletes the deletion marker from the local directory.

The method continues at step 218 where the processing module determineswhether storing the encoded data slice is allowable when the writerequest does not pertain to deleting the encoded data slice, wherein theencoded data slice is received with the write request. The determiningwhether the storing the encoded data slice is allowable includes atleast one of indicating that storing the received encoded data slice isallowable when the received encoded data slice is associated with adirectory file (e.g., based on a flag, a query, directory informationassociated with the write request, matching a slice name, a message, anda command), indicating that storing the received encoded data slice isallowable when memory availability compares favorably to a memoryavailability threshold, and indicating that storing the received encodeddata slice is allowable when utilization of the memory space comparesfavorably to a memory space usage threshold. The method branches to step222 when the processing module determines that storing the encoded dataslice is allowable. The method continues to step 220 when the processingmodule determines that storing the encoded data slice is not allowable.The method continues at step 220 where the processing module sends anerror response message to a requesting entity when the storing is notallowable. The method continues at step 222 where the processing modulestores the received encoded data slice when the storing is allowable.

FIG. 12 is a flowchart illustrating an example of determining storagegeneration operational modes. The method begins with step 240 where aprocessing module (e.g., of a dispersed storage (DS) processing module)determines generations based on one or more of a generation list, whichgeneration the process left off with last time, an error message, avault identifier, a message, and a command. The method continues at step242 where the processing module determines a status of DS unit storagesets associated with the generations, wherein the DS unit storage setdeterminations are based on one or more of a lookup, a query, a list, amessage, and a command. The status may include one or more of a pingtime, a write speed indicator, a read speed indicator, an availabilityhistory, a reliability history, cost, power availability, andutilization. The method continues at step 244 where the processingmodule determines loading requirements. The loading requirements includeat least one of read operations per unit of time and write operationsper unit of time. The determination may be based on one or more of aread history record, a write history record, a number of readerspredictor, a number of writers predictor, a read activity predictor, anda write activity predictor. For example, the processing moduledetermines the loading requirements to include 15,000 read operationsper minute and 1,000 write operations per minute based on aggregatingthe historical and predictive records.

The method continues at step 246 where the processing module determineswhich generations to be write capable based on one or more of a statusof the DS unit storage sets, the loading requirements, systempreferences, a message, and a command. For example, the processingmodule determines DS unit storage set 500 to be write capable when thestatus of DS unit storage set 500 indicates that memory utilization isless than a utilization threshold. As another example, the processingmodule determines DS unit storage sets 430, 395, and 632 to be writecapable when the loading requirements indicates a number of predictedwriters is greater than a number of writers threshold. In such aninstance, a system performance improvement is realized by activatingmultiple DS unit storage sets to process write sequence activity frommany writers.

The method continues at step 248 where the processing module determineswhich generations to be read capable based on one or more of the statusof the DS unit storage sets, the loading requirements, systempreferences, a message, and a command. For example, the processingmodule determines DS unit storage set 700 to be read capable when thestatus of DS unit storage set 600 indicates that memory utilization isnear a utilization threshold. As another example, the processing moduledetermines DS unit storage sets 111, 327, and 948 to be read capablewhen the loading requirements indicates a number of predicted readers isgreater than a number of readers threshold. In such an instance, asystem performance improvement is realized by activating multiple DSunit storage sets to process read sequence activity from many readers.

The method continues at step 250 where the processing module determinesgeneration modes. The generations modes includes one or more of DS unitpower off, DS unit power on, DS unit memory spin down, DS unit memoryspin up, DS unit off-line, and DS unit online. Such a determination maybe based on one or more of which generations are write capable, whichgenerations are read capable, status of the DS unit storage sets,loading requirements, system preferences, a message, and a command. Forexample, the processing module determines the generation mode for DSunit storage set 948 to be DS unit memory spin down when loadingrequirements indicates that system performance is satisfactory withoututilizing DS unit storage set 948. The method continues at step 252where the processing module sends mode control request messages to theDS unit storage sets in accordance with the generation modes.

FIG. 13 is a flowchart illustrating an example of manipulating pre-slicedata. The method begins with step 254 where a processing module (e.g.,of a dispersed storage (DS) processing unit) receives a data segment.For example, a processing module receives the data segment with metadataassociated with the data segment. The metadata may include one or moreof a data object name, a data object type, magic values, headerinformation, data object content attributes, data object size, a useridentifier (ID), a priority indicator, a security indicator, anintegrity check indicator, an encryption indicator, a compressionindicator, and a performance indicator. The method continues at step 256where the processing module determines whether to statistically test thedata segment. The determination may be based on the metadata. Forexample, the processing module determines to not statistically test thedata segment when the metadata indicates that a file name extension isassociated with a data object type that is already compressed. Themethod branches to step 264 when the processing module determines to notstatistically test the data segment. The method continues to step 258when the processing module determines to statistically test the datasegment.

The method continues at step 258 where the processing modulestatistically tests the data segment to determine compressibility. Forexample, the processing module compresses a portion of the data segmentand compares a resulting compressed portion to the portion to determineif the difference is more than a compressibility threshold. The methodcontinues at step 260 where the processing module determines whether toapply a compression codec based on the statistical test. For example,the processing module determines to not apply the compression codec whenthe statistical test indicates that the difference between thecompressed portion and a portion is less than the compressibilitythreshold. The method branches to step 264 when the processing moduledetermines to not apply the compression codec. The method continues tostep 262 when the processing module determines to apply the compressioncodec. The method continues at step 262 where the processing moduledetermines the compression codec when the processing module determinesto apply the compression codec. The determination may be based on one ormore of the statistical test (e.g., compressibility), a compressioncodec table lookup, a compression codec matching algorithm, a message,and a command.

The method continues at step 264 where the processing module determineswhether to apply an encryption codec based on determining whether thedata segment is already encrypted. For example, the processing moduleanalyzes the data segment to determine a randomness factor and comparesthe randomness factor to a randomness threshold. Next, the processingmodule indicates to apply the encryption codec when the comparisonindicates that the randomness factor is greater than the randomnessthreshold. As another example, the processing module determines that thedata segment is encrypted based on the security indicator and/orencryption indicator of the metadata. The method branches to step 268when the processing module determines to not apply the encryption codec.The method continues to step 266 when the processing module determinesto apply the encryption codec. The method continues at step 266 wherethe processing module determines the encryption codec when theprocessing module determines to apply the encryption codec. Thedetermination may be based on one or more of the randomness factor, thesecurity indicator, the encryption indicator, an encryption codec tablelookup, an encryption codec matching algorithm, a message, and acommand.

The method continues at step 268 where the processing module determineswhether to apply an integrity check codec based on determining whetheran integrity check has already been applied to the data segment. Forexample, the processing module analyzes the data segments to determineif one or more of a signature, a hash, a checksum have been applied. Asanother example, the processing module determines that the integritycheck has already been applied to the data segment based on theintegrity check indicator of the metadata. The method branches to step272 when the processing module determines to not apply the integritycheck codec. The method continues to step 270 when the processing moduledetermines to apply the integrity check codec. The method continues atstep 270 where the processing module determines the integrity checkcodec when the processing module determines to apply the integrity checkcodec. The determination may be based on one or more of the integritycheck determination, the integrity check indicator, an integrity checkcodec table lookup, an integrity check codec matching algorithm, amessage, and a command.

The method continues at step 272 where the processing module performsthe codec functions on the data segment in accordance with thecompression codec, the encryption codec, and the integrity check codecas previously determined. For example, the processing module applies allthree codec types to the data segment when all three codec types aredesired. As another example, the processing module applies none of thethree codec types to the data segment when none of the codec types aredesired. As yet another example, the processing module applies one codectype but not the other two codec types. In addition, the processingmodule may update a codec stack to indicate the ordering of the codecfunctions as applied to the data segment to enable subsequent post-slicedata de-manipulation in the reverse order. The method may continue toapply more codecs to the data segment in the same or more categories.For example, the processing module may apply the compression codec, theencryption codec, a second encryption codec and the integrity checkcodec.

FIG. 14 is a flowchart illustrating an example of error correcting adata slice. The method begins with step 274 where a processing module(e.g., a dispersed storage (DS) processing unit) receives a data segmentretrieval request. For example, the processing module retrieves aplurality of data segments to re-create a data object by generating aplurality of retrieval requests for the plurality of data segments. Themethod continues at step 276 where the processing module generates aplurality of data slice retrieval requests to retrieve a decodethreshold number of error coded data slices in response to receiving thedata segment retrieval request. For example, the processing modulereceives a source name associated with the data segment, determines aplurality of slice names for the data segment, determines a plurality ofDS units associated with the plurality of slice names, and sends theplurality of data slice retrieval requests to the plurality of DS units.At step 276, the processing module receives a decode threshold number oferror coded data slices in response to the plurality of retrievalrequests.

The method continues at step 278 where the processing module decodes theerror coded data slices in accordance with an error coding dispersalstorage function to produce a decoded data segment and a validityindicator. For example, the processing module calculates a hash of thedecoded data segment to produce the validity indicator. At step 278, theprocessing module determines whether the decoded data segment is validby comparing a stored validity indicator (e.g., associated with the datasegment) with the validity indicator. The processing module determinesthat the decoded data segment is valid when the stored validityindicator and the validity indicator are substantially the same. Themethod branches to step 282 when the processing module determines thatthe decoded data segment is not valid. The method continues to step 280when the processing module determines that the decoded data segment isvalid. The method continues at step 280 where the processing moduleutilizes the decoded data segment as the data segment when theprocessing module determines that the decoded data segment is valid.

The method continues at step 282 where the processing module determinesa pillar combination such that the pillar combination specifies whichpillars to retrieve and utilize data slices in an attempt to re-create avalid decoded data segment. Such a determination may be based on one ormore of the pillar width, the threshold, a number of pillarcombinations, which pillar combinations resulted in a previous test witha valid decoded data segment, and which pillar combinations resulted ina previous test with an invalid the decoded data segment. The processingmodule may utilize one or more techniques to determine the one or moredata slices in error. For example, the processing module may choose toutilize slices from different pillar groups to initially determine wherean error is sourced from. In an instance, the processing module maychoose to utilize pillars 1-3 in a first test and pillars 3-5 in asecond test when the pillar width is 5 and the threshold is 3. Asanother technique, the processing module may eliminate one pillar at atime. In an instance, the processing module may choose to utilize thefollowing pillar combinations to eliminate pillar 2: 1, 3, 4; 1, 3, 5;1, 4, 5 ; and 3, 4, 5.

The method continues at step 284 where the processing module retrieveserror coded data slices of other pillar(s) in accordance with the pillarcombination. The processing module may retrieve data slices of all ofthe pillars at once and subsequently perform the validity testing ofdecoded data segments from different combinations of pillars. The methodcontinues at step 286 where the processing module decodes the errorcoded data slices in accordance with the error coding dispersal storagefunction to produce a subsequent decoded data segment and a subsequentvalidity indicator. At step 286, the processing module determineswhether the subsequent decoded data segment is valid. The methodbranches back to step 282 (e.g., to try another pillar combination) whenthe processing module determines that the subsequent decoded datasegment is not valid. The method continues to step 290 when theprocessing module determines that the subsequent decoded data segment isvalid.

The method continues at step 290 where the processing module utilizesthe subsequent decoded data segment as the data segment when theprocessing module determines that the subsequent data segment is valid.Alternatively, or in addition to, the processing module may end thetesting loop when the error status has been determined for each dataslice (e.g., each of the data slices in error have been identified).Alternatively, the process fails if all possible pillar combinationshave been tried without producing a valid subsequent decoded datasegment.

The method continues at step 292 where the processing module encodes thedata segment in accordance with the error coding dispersal storagefunction to produce an error-free set of error coded data slices. Themethod continues at step 294 where the processing module compares theretrieved error coded data slices to the error-free set of error codeddata slices to identify the retrieved error coded data slice(s) (andpillars) in error (e.g., a difference signifies an error). The methodcontinues at step 296 where the processing module sends an error-freeerror coded data slice to a DS unit, wherein the DS unit corresponds tothe pillar of the retrieved error coded data slice in error. The DS unitreplaces the error coded data slice in error with the error-free errorcoded data slice. Alternatively, or in addition to, the processingmodule initiates a rebuilding process to identify and repair data slicesin error.

FIGS. 15A-15D depict an example of a dispersed storage network (DSN)memory where a first plurality of DS units 36 are implemented in a locallocation and a second plurality of DS units 36 are implemented in aremote location. For example, the local location is proximate to a DSprocessing unit utilized to store and retrieve data slices to the DSNmemory and the remote location is not proximate to the DS processingunit and the local location. As such, the network 24 operably couplesthe DS processing unit to the plurality of DS units 36 at the remotelocation. FIGS. 15A-15D individually depict configuration examples oferror coding dispersal storage function parameters (e.g., pillar width,threshold) and pillar assignments to DS units of one or both of theplurality of DS units. Note that the configurations are associated witha storage policy that includes optimization objectives such as cost,reliability, security, and performance. The configurations andobjectives are discussed in greater detail with reference to FIGS.15A-15 D. A method to determine and implement the configuration of thestorage policy is discussed in greater detail with reference to FIG. 16.

FIG. 15A is a schematic block diagram of an embodiment of a pillarassignment of a dispersed storage network (DSN) memory. The DSN memoryincludes a plurality of dispersed storage (DS) units 36 at a locallocation 298 and a plurality of DS units 36 at a remote location 300.Combinations of DS units 36 from one or both of the local location 298and the remote location 300 may be assigned to form a DS unit storageset in accordance with a system design objective, wherein the DS unitstorage set accommodates storing a pillar width number (n) of encodeddata slices as a set of encode slices. For example, pillars 1-5 of a setof encoded data slices are assigned to five DS units 36 of the locallocation 298 when a pillar width n=5 and a decode threshold k=3 (e.g.,no pillars of the set of encoded data slices are assigned to DS units ofthe remote location 300). Such a configuration may be associated with asystem designed objective of low-cost since utilized DS units 36 are alllocated at the local location 298 (e.g., no remote location 300 costs)and the pillar width is relatively low as compared to otherconfigurations thus lowering costs associated DS units 36.

FIG. 15B is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. The DSN memoryincludes a plurality of dispersed storage (DS) units 36 at a locallocation 298 and a plurality of DS units 36 at a remote location 300. Inan implementation example, pillars 1-3 of a set of encoded data slicesare assigned to three DS units 36 of the local location 298 and pillars4-5 of the set of encoded data slices are assigned two DS units 36 ofthe remote location 300 when a pillar width n=5 and a decode thresholdk=2. Such a configuration may be associated with a system designedobjective of improved reliability since a decode threshold number ofpillars are included in both the local location 298 and the remotelocation 300. As such, data may be retrieved from one location even whenthe other location is not available

FIG. 15C is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. The DSN memoryincludes a plurality of dispersed storage (DS) units 36 at a locallocation 298 and a plurality of DS units 36 at a remote location 300. Inan implementation example, pillars 1-5 of a set of encoded data slicesare assigned to five DS units 36 of the local location 298 and pillars6-10 of the set of encoded data slices are assigned five DS units 36 ofthe remote location 300 when a pillar width n=10 and a decode thresholdk=6. Such a configuration may be associated with a system designedobjective of improved security since the decode threshold is relativelyhigh with respect to the pillar width, encoded data slices of thepillars are stored in more than one location, and a decode thresholdnumber of encoded data slices does not exist at a single location.

FIG. 15D is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. The DSN memoryincludes a plurality of dispersed storage (DS) units 36 at a locallocation 298 and a plurality of DS units 36 at a remote location 300. Inan implementation example, pillars 1-5 of a set of encoded data slicesare assigned to five DS units 36 of the local location 298 and pillars6-10 of the set of encoded data slices are assigned five DS units 36 ofthe remote location 300 when a pillar width n=10 and a decode thresholdk=4. Such a configuration may be associated with a system designedobjective of improved reliability since a decode threshold number ofpillars are stored in both locations and the decode threshold isrelatively low with respect to the pillar width. As such, there are 210ways (e.g., 10 choose 4) to successfully retrieve a decode thresholdnumber of encoded data slices from DS units 36 of the remote location298 and the remote location 300.

FIG. 16 is a flowchart illustrating an example of implementing a storagepolicy. The method begins with step 302 where a processing module (e.g.,of a dispersed storage (DS) processing unit) determines a currentstorage policy. The current storage policy may include one or more of astoring policy, a retrieving policy, an aggregate storing and retrievingpolicy. The determination may be based on one or more of a lookup, aquery, a list, a message, and a command. The method continues at step304 where the processing module determines storage requirements, whereinthe requirements include one or more objectives related to cost,reliability, performance, and security. The determination may be basedon one or more of a cost requirement, a reliability requirement, aperformance requirement, a security requirement, a user input, anindicator, an error message, a request, a message, and a command.

The method continues at step 306 where the processing module determinesa new storage policy based on one or more of the current storage policy,a policy guideline, minimum requirements, and the storage requirements.For example, the processing module determines a new storage policy tolower costs when there was no current storage policy and the storagerequirements indicate a low-cost is favored over other objectives. Asanother example, the processing module determines the new storage policyto optimize reliability when the current storage policy is optimized forcost and the storage requirements indicate that reliability is nowpreferred over cost.

The method continues at step 308 where the processing module determinesavailable storage resources (e.g., DS units, locations of DS units,network connectivity availability, etc.). The determination may be basedon one or more of a table lookup, a list, a query, a message, and acommand. For example, the processing module determines the availableresources to include a first group of five DS units at a local locationand a second group of five DS units at a remote location. The methodcontinues at step 310 where the processing module determines anoptimized configuration of storage resources based on the new storagepolicy and the available storage resources. The determination includesselecting one alternative configuration of a plurality of alternativeconfigurations of the storage resources based on evaluating a fit of thealternative configuration to the new storage policy and storagerequirements. The evaluation may include analyzing individual parametersof cost, reliability, and security.

The method continues at step 312 where the processing module determineswhether cost optimization is required based on the optimizedconfiguration. The method branches to step 316 when the processingmodule determines that cost optimization is not required. The methodcontinues at step 314 where the processing module optimizes theconfiguration for cost (e.g., one location, a small pillar width) whenthe processing module determines to optimize for cost. The methodcontinues at step 316 where the processing module determines whetherreliability optimization is required based on the optimizedconfiguration. The method branches to step 320 when the processingmodule determines that reliability optimization is not required. Themethod continues at step 318 where the processing module optimizes theconfiguration for reliability (e.g., greater than one location, a smallthreshold) when the processing module determines to optimize forreliability. The method continues at step 320 where the processingmodule determines whether security optimization is required based on theoptimized configuration. The method branches to step 324 when theprocessing module determines that security optimization is not required.The method continues that step 322 where the processing module optimizesthe configuration for security (e.g., greater than one location, alarger threshold) when the processing module determines to optimize forsecurity.

The method continues at step 324 where the processing module determineswhether to move slices based on the optimized configuration. Forexample, the processing module determines to move slices from a DS unitof the local location to a DS unit of the remote location to addressimproved reliability and/or or security. The method branches to step 328when the processing module determines to not move slices. The methodcontinues at step 326 where processing module moves error coded dataslices when the processing module determines to move data slices. Themethod continues at step 328 where the processing module determineswhether to re-encode error coded data slices based on the optimizedconfiguration. For example, the processing module determines tore-encode when changing error coding dispersal storage functionparameters (e.g., a new pillar width, a new threshold). The methodbranches to step 332 when the processing module determines to notre-encode error encoded data slices. The method continues at step 330where the processing module re-encodes error coded data slices (e.g.,retrieve the old slices, decode the old slices to produce a datasegment, encode the data segment to produce re-encoded data slices,store the re-encoded data slices, delete the old slices) when theprocessing module determines to re-encode error coded data slices. Themethod continues at step 332 where the method ends.

FIGS. 17A-17C depict an example of a dispersed storage network (DSN)memory that includes a variable number of dispersed storage (DS) units36 depicting a migration scenario from a starting step of FIG. 17 A, toa mid-step of FIG. 17 B, to an ending step of FIG. 17 C. At each step,the DS units 36 are assigned pillars of a corresponding set of encodeddata slices in accordance with error coding dispersal storage functionparameters (e.g., pillar width, decode threshold, etc.). The migrationscenario steps support migration objectives including expanding andcontracting storage resources. For example, the storage resources may beexpanded to support a migration objective to add more DS units 36 and/orretire older DS units 36. As another example, the storage resources maybe contracted support a migration objective to shrink a number of DSunits 36. As illustrated, the DS units 36 of FIGS. 17A-17C areconfigured to support a migration objective to retire three of five DSunits by adding three DS units, temporarily resulting in eight DS units36, followed by retirement of three original DS units 36 to end thescenario with five DS units 36. The migration objectives andconfigurations are discussed in greater detail with reference to FIGS.17A-17 C. A method to expand and contract storage resources is discussedin greater detail with reference to FIG. 18.

FIG. 17A is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. Five dispersedstorage (DS) units 36 correspond to a step 1 of a migration scenariowhen a pillar width is 5 and a decode threshold is 3. A migrationobjective may include retiring three of the five DS units 36. Forexample, the three DS units 36 may have aged past a DS unit agethreshold where it is desired to retire DS units that have aged past thethreshold. As another example, error messages and/or performance historymay indicate that the three DS units 36 should be retired.

FIG. 17B is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. Three dispersedstorage (DS) units 36 are newly provisioned resulting in eight DS units36 correspond to a step 2 of a migration scenario when a pillar width isexpanded to 8 and a decode threshold remains 3. As such, the three newlyprovisioned DS units 36 are assigned to expansion pillars 6 -8. Amigration objective may include retiring a first three of an initialfive DS units 36 without moving encoded data slices from the first threeDS units 36.

At step 2 of the migration scenario, encoded data slices correspondingto the expansion pillars are generated and stored in the three expansionDS units 36. For example, a decode threshold number of encoded dataslices are retrieved from the initial five DS units 36, the encodedslices are decoded in accordance with an error coding dispersal storagefunction (e.g., n=5) to produce a data segment, the data segment isencoded in accordance with new error coding dispersal storage functionparameters (e.g., n=8) to produce encoded data slices corresponding tothe expansion pillars.

FIG. 17C is a schematic block diagram of another embodiment of a pillarassignment of a dispersed storage network (DSN) memory. Three dispersedstorage (DS) units 36 of an initial five DS units 36 are retiredresulting in five DS units 36 correspond to a step 3 of a migrationscenario when a pillar width was expanded to 8 and a decode thresholdremains 3. As such, there is no need to modify encoded data slices ofthe remaining three DS units 36 corresponding to pillars 4-6 since datasegments can be successfully decoded based on retrieving a decodethreshold number (e.g., 3 pillars) of data slices from any of theremaining DS units. In such a migration scenario, a total number of DSunits 36 and the decode threshold is the same in steps 1 and 3 and thereare still 5 choose 3 ways to retrieve the decode threshold number ofencoded data slices.

FIG. 18 is a flowchart illustrating an example of expanding andcontracting storage resources. The method begins with step 334 where aprocessing module (e.g., dispersed storage (DS) processing unit)determines storage performance based on one or more of a query, anderror message, a lookup, a message, and a command. Storage performancemay include one or more of memory device uptime, mean time to failure,mean time to repair, access latency, access bandwidth, and networkperformance. The method continues at step 336 where the processingmodule determines a storage provisioning schedule based on one more ofthe storage performance, storage requirements, a previous schedule, acommand, a lookup, a query, a request, and a message. The storageprovisioning schedule may include one or more of an expansionrequirement, a contraction requirement, a provisioning schedule, and ade-provisioning schedule.

The method continues at step 338 where the processing module determineswhether to expand storage. Expansion of storage may include one more ofadding memory devices, adding DS units, adding a dispersed storagenetwork (DSN) memory, activating dormant storage, and allocating morememory of already provisioned memory devices. The determination may bebased on one or more of the provisioning schedule, the storageperformance, an expansion indicator, a storage requirement, and acomparison of the storage performance to the requirement. For example,the processing module determines to expand storage when the storageprovisioning schedule indicates that more storage is to be added whenthe storage performance indicates a 10% fall of the mean time to failurein any ten day period. The method branches to step 344 when theprocessing module determines to not expand storage. The method continuesto step 340 when the processing module determines to expand storage.

The method continues at step 340 where the processing module facilitatesprovisioning and allocation of storage. For example, the processingmodule sends a message to a DS managing unit communicating a need to addmore DS units to a system. As another example, the processing moduleactivates dormant DS units. As yet another example, the processingmodule allocates more memory of an existing DS unit to a vault. As astill further example, the processing module determines a new pillarwidth. The method continues at step 342 where the processing moduleencodes and stores slices. For example, the processing module re-encodesdata slices in accordance with a new pillar width and stores re-encodeddata slices in newly allocated storage. As another example, theprocessing module retrieves encoded data slices of a corresponding vaultand sends the encoded data slices to the newly allocated storage.

The method continues at step 344 where the processing module determineswhether to contract storage. Contraction of storage may include one moreof deactivating memory devices, removing DS units, deactivating DSunits, removing a DSN memory, turning off active storage, andde-allocating memory of provisioned memory devices. The determinationmay be based on one or more of a de-provisioning schedule, storageperformance, a contraction indicator, a storage requirement, and acomparison of the storage performance to a requirement. For example, theprocessing module determines to contract storage when the storagede-provisioning schedule indicates that storage is to be removed whenthe storage performance indicates a 20% rise of the mean time to failurein any ten day period. The method repeats back to step 334 when theprocessing module determines to not contract storage. The methodcontinues to step 346 when the processing module determines to contractstorage.

The method continues at step 346 where the processing module facilitatesde-provisioning and de-allocation of storage. The de-provisioning andde-allocation may include one or more of deactivating a memory device,deactivating a DS unit, deactivating a DSN memory, de-allocating memoryfrom one or more faults, turning off the memory device, turning off a DSunit, and retrieving slices from a primary memory device and storingthem in a different memory device or DS unit followed by turning off theprimary memory device. The method repeats back to step 334.

FIG. 19 is a schematic block diagram of an embodiment of a communicationsystem. The system includes a site 1, a site 2, a user device 1, and auser device 2. The site 1 includes a DS processing module 1 and aplurality of n transmitter receiver (TR) modules 11-1n. The site 2includes a DS processing module 1 and a plurality of n TR modules 21-2n.The user device 1 and the user device 2 includes a DS processing module34 and a plurality of n TR modules 1-n. The TR modules may beimplemented as at least one of n wireless hardware transceivers or fewerthan n frequency multiplexed, time multiplexed, or the like, as nsoftware modules operating on one hardware transceiver (e.g., a softwaredefined radio (SDR)), and as n software modules operating on two or morehardware transceivers (e.g., software defined radios).

The DS processing modules 1-2 receive broadcast content 348 (e.g.,video, multimedia, audio, music, voice, data streaming, etc.), determineerror coding dispersal storage function parameters, encode the broadcastcontent to produce error encoded data slices of n pillars in accordancewith the error coding dispersal storage function parameters, determine awireless configuration, configure TR modules 11-1n and 21-2n inaccordance with the wireless configuration, and send the error encodeddata slices via the TR modules to produce pillar 1-n communication aswireless signals. For example, DS processing module 1 sends errorencoded data slices of all 16 pillars from TR modules 11-1n as wirelesssignals when a pillar width is 16 (e.g., pillar 1 communication from TRmodule 11, pillar 2 communication from TR module 12, pillar 3communication from TR module 13, etc.). As another example, DSprocessing module 2 sends pillar 3 communication from TR module 23,through sending pillar 16 communications from TR module 2n when thepillar width is 16. The method of operation of the DS processing modules1-2 is discussed in greater detail with reference to FIG. 21.

The TR modules communicate wireless signals with other TR modules of thesystem and may operate in accordance with one or more wireless industryprotocol standards including but not limited to universal mobiletelecommunications system (UMTS), global system for mobilecommunications (GSM), long term evolution (LTE), wideband code divisionmultiplexing (WCDMA), IEEE 802.11, IEEE 802.16, WiMax, Bluetooth, or anyother local area network (LAN), wide area network (WAN), personal areanetwork (PAN) or like wireless protocol. As such, any two, four, or anynumber of TR modules may utilize one or more of the same or differentwireless protocols. For example, TR module 11 may utilize GSM and TRmodule 12 may simultaneously utilize IEEE 802.16.

The TR modules 1-n may utilize similar or different performance levels(e.g., speed in bits per second) of the wireless signals. For example,TR module 14 may communicate at 100 kilo bits per second (Kbps) viapillar 4 communication wireless signals in accordance with the WCDMAstandard and TR module 17 may simultaneously communicate at 3.3 megabits per second (Mbps) via pillar 7 communication wireless signals inaccordance with IEEE 802.11 standard. As another example, TR module 14and TR module 17 may both function in accordance with the IEEE802.16standard but operate at different performance levels. For instance, TRmodule 14 may communicate at 350 kilo bits per second via pillar 4communication wireless signals in accordance with the IEEE 802.16standard and TR module 17 may simultaneously communicate at 675 kilobits per second via pillar 7 communication wireless signals inaccordance with IEEE 802.16 standard. Since software defined radios arepossible in some embodiments, such protocols may be changed over timeaccording to a predetermined security algorithm whereby the protocol ischanging over time.

Site 1 and site 2 communicate with each other to facilitate coordinationof the transmission of pillar communications. For example, suchcoordination communication is facilitated via a wireless inter-sitecommunication 350. As another example, the coordination communication isfacilitated via a wireline inter-site communication. In an example ofcoordination, site 1 sends a message to site 2 that site 1 will transmitpillars 1-5 and site 2 will transmit pillars 6-8 of the same datasegment when the pillar width is 8.

The DS processing module 34 of user device 1 or 2 receives the broadcastcontent by determining a wireless configuration for TR modules 1-n,configuring the TR modules in accordance with the wirelessconfiguration, determining error coding dispersal storage functionparameters, receiving pillar communication via of the TR modules,decoding received data slices from the pillar communication inaccordance with the error coding dispersal storage function parametersto produce the broadcast content 348. For example, user device 1receives pillar 1-n communications from site 1 to receive a decodethreshold number of error encoded data slices to decode reproducing thebroadcast content 348. As another example, user device 2 receives pillar1-2 communications from site 1 and pillar 3-n communications from site 2to receive a decode threshold number of error encoded data slices todecode producing the broadcast content 348. As yet another example, userdevice 2 receives pillar 1-2 communications from user device 1 via aninter-device wireless communication 352 and pillar 3-n communicationsfrom site 2 to receive a decode threshold number of error encoded dataslices to decode reproducing the broadcast content 348. The inter-devicewireless communications 352 is utilized to communicate pillarcommunications and coordination information between two or more userdevices. The coordination information includes requests and responses toforward particular pillar communications. For example, user device 2sends a pillar 1-2 communication request via the inter-device wirelesscommunication 352 to user device 1. User device 1 forwards pillar 1-2communications to user device 2 via inter-device wireless communications352 in response. The method of operation of the DS processing module ofthe user devices 1-2 is discussed in greater detail with reference toFIGS. 20, 23, and 24.

FIG. 20 is a flowchart illustrating an example of acquiring a contentbroadcast. The method begins with step 354 where a processing module(e.g., of a user device) determining a mapping of encoded data slices towireless channels for wireless communication of data, wherein a datasegment of the data is encoded in accordance with a dispersed storageerror encoding protocol to produce a set of encoded data slices andwherein a first encoded data slice of the set of encoded data slices isassociated with a first wireless channel of a set of wireless channels.The mapping includes one or more of a pillar to wireless channelmapping, wherein the dispersed storage error encoding protocolprescribes a set of pillars, a data segment to wireless channel mapping,and an encoded data slice pattern to wireless channel mapping (e.g., acombination of pillars and segments).

As a mapping example, the processing module determines to receivepillars 1-2 from site 1 and pillars 3-16 from site 2 when the processingmodule determines that pillars 1-2 can only be received from site 1 andpillars 3-16 can only be received from site 2. As another example, theprocessing module determines to receive pillars 1-8 from site 1 andpillars 9-16 from site 2 when all 16 pillars are transmitted from bothsites and the wireless signal quality indicator indicates that pillar1-8 communications from site 1 is preferred to pillar 1-8 communicationsfrom site 2 and that pillar 9-16 communications from site 2 is preferredto pillar 9-16 communications from site 1. As yet another example, theprocessing module determines wireless parameters to optimize a resultingwireless signal quality indicator. For instance, the processing moduledetermines to utilize a slower wireless signal to improve reliability ofthe wireless communications.

The determining of the mapping may be based on at least one of receivinga broadcast indicator, a broadcast status indicator, a user device datarequirement (e.g., another user device desires the same data segment), apreviously utilized access method, a data access response, a message, apillar broadcast indicator, and a wireless signal indicator. Forexample, the processing module determines the mapping to include a firstmapping of a first collective of encoded data slices of the set ofencoded data slices to at least one wireless channel of a firsttransmission site and a second mapping of a second collective of encodeddata slices of the set of encoded data slices to at least one wirelesschannel of a second transmission site.

The method continues at step 356 where the processing module configures,in accordance with the mapping, receivers of a wireless communicationdevice to receive, via a set of wireless channels, at least some of theset of encoded data slices to produce configured receivers. Theconfiguring the receivers includes configuring a first receiver of thereceivers to receive the first encoded data slice via a first wirelesschannel of the set of wireless channels, configuring a second receiverof the receivers to receive a second encoded data slice of the set ofencoded data slices via a second wireless channel of the set of wirelesschannels, and configuring a third receiver of the receivers to receive athird encoded data slice of the set of encoded data slices via a thirdwireless channel of the set of wireless channels. At step 356, theprocessing module configures, in accordance with the mapping, a firstreceiver of the receivers to receive at least some of the set of encodeddata slices via a first wireless channel of the set of wireless channelsand a second receiver of the receivers to receive at least some of thesecond set of encoded data slices via a second wireless channel of theset of wireless channels when a second data segment of the data isencoded in accordance with the dispersed storage error encoding protocolto produce a second set of encoded data slices.

At step 356, the processing module may generate a configuration signalregarding optimal operational characteristics of at least one of theconfigured receivers and facilitate transmission of the configurationsignal. For example, the processing module facilitates transmission ofthe configuration signal to a transmitter corresponding to at least onereceiver such that transmitter configuration includes information of theconfiguration signal.

The method continues at step 358 where the processing module facilitatesthe configured receivers to receive encoded data slices of the set ofencoded data slices to produce received encoded data slices. At step358, the processing module facilitates the first receiver to receive theencoded data slices of the set of encoded data slices to produce thereceived encoded data slices and facilitates the second receiver toreceive encoded data slices of the second set of encoded data slices toproduce second received encoded data slices when the second data segmentof the data is encoded in accordance with the dispersed storage errorencoding protocol to produce the second set of encoded data slices.

The method continues at step 360 where the processing module determineswhether at least a decode threshold number of received encoded dataslices have been received within a predetermined period of time. At step360, the processing module determines whether at least a decodethreshold number of the second received encoded data slices have beenreceived when the second data segment of the data is encoded inaccordance with the dispersed storage error encoding protocol to producethe second set of encoded data slices. The method branches to step 364when the processing module determines that the decode threshold numberof received encoded data slices have not been received within thepredetermined period of time. The method continues to step 362 when theprocessing module determines that the decode threshold number ofreceived encoded data slices have been received.

The method continues at step 362 where the processing module decodes thereceived encoded data slices to recapture the data segment when at leastthe decode threshold number of received encoded data slices have beenreceived. At step 362, the processing module decodes the second receivedencoded data slices to recapture the second data segment when at leastthe decode threshold number of the second received encoded data sliceshave been received. Alternatively, the method may loop back to step 360when more data segments are to be recaptured.

The method continues at step 364 where the processing module determineswhether the mapping is sub-optimal based on wireless communicationconditions when the decode threshold number of encoded data slices havenot been received within the predetermined period of time. Thedetermining whether the mapping is sub-optimal includes at least one ofdetermining that a performance indicator associated with at least one ofthe configured receivers compares unfavorably to a performance thresholdand determining that a signaling indicator associated with the at leastone of the configured receivers compares unfavorably to the performancethreshold. The performance indicator includes one or more of a receivedbit rate, a number of encoded slices received per second, a number ofpillars received per second, which pillars are being received, and whichpillars are not been received. The signaling indicator includes one ormore of a received bit rate, a received bit error rate, an interferencelevel, a loss of wireless signal indicator, and a wireless signal levelindicator.

The method repeats back to step 362 continue to receive encoded dataslices when the processing module determines that the mapping is notsub-optimal. The method continues to step 366 when the processing moduledetermines that the mapping is sub-optimal. The method continues at step366 where the processing module determines a second mapping of encodeddata slices to wireless channels based on the wireless communicationconditions when the mapping is sub-optimal. The method loops back tostep 356 to configure receivers in accordance with the second mapping.

FIG. 21 is a flowchart illustrating an example of generating a contentbroadcast. The method begins with step 390 where a processing module(e.g., of a dispersed storage (DS) processing unit) determines data tobroadcast based on one or more of a data segment indicator, a next datasegment of a data object indicator, an application request, a userinput, a message, a request from a user device, a request from a site,and a command. The method continues at step 392 where the processingmodule determines a wireless configuration based on one or more of aquality level indicator of a wireless communications path from a site toone or more user devices, user devices within wireless range, requiredpillars, and which pillars are being transmitted by which transceiver(TR) module. The wireless configuration may include one or more ofwireless parameters for the TR modules, configuring TR modules tobroadcast particular pillars, and indicating that one or more othersites and/or user devices broadcast particular pillars.

The method continues at step 394 where the processing module configuresthe wireless. The configuring includes sending wireless configurationinformation to TR modules associated with one or more sites and/or oneor more user devices. The method continues at step 396 where theprocessing module encodes a data segment in accordance with an errorcoding dispersal storage function to produce error coded data slices.The method continues at step 398 where the processing module sends theerror coded data slices utilizing the TR modules as pillarcommunications via wireless signals. The method continues at step 400where the processing module determines whether enough data has been sentbased on one or more of a number of data segments in the data object, anumber of data slices sent, a number of data segments sent, a number ofoutstanding data segments to be sent, and a number of outstanding dataslices to be sent. The method branches back to step 390 when theprocessing module determines that enough data has been sent. The methodcontinues to step 402 when the processing module determines that notenough data has been sent.

The method continues at step 402 where the processing module determineswhether to reconfigure the wireless based on one or more of monitoring awireless signal quality level indicator indicating performance of thewireless communications paths (e.g., receiving feedback from one or moreuser devices), a performance threshold, and comparing the wirelesssignal quality level to the performance threshold. For example, theprocessing module determines to reconfigure the wireless when receivinga request from a user device to start sending more pillars via aparticular wireless communications path that is more favorable for theuser device. As another example, the processing module determines toreconfigure the wireless to increase the speed of a TR module whenreceiving a message from a user device that indicates that atransmission speed is too slow on an associated wireless communicationspath. As yet another example, the processing module determines toreconfigure the wireless to align with a configuration objective (e.g.,cost, performance, reliability, a balance between these factors, etc.)where the configuration objective may be determined based on apredetermination, a lookup, a user device requests, a performance drivendynamic, and from another site. Configuration objectives, wirelessconfiguration, and pillars assignments are discussed in greater detailwith reference to FIG. 22. The method branches back to step 396 when theprocessing module determines not to reconfigure the wireless. The methodbranches back to step 392 when the processing module determines toreconfigure the wireless.

FIG. 22 is a table illustrating an example of wireless configuration andpillar assignments 420. The wireless configuration and pillarassignments 420 represents pillar number and communication speedassignments for each transceiver (TR) of a plurality of TR modules 1-5in accordance with an optimization objective when a pillar width isfive. The optimization objectives includes cost, performance,reliability, balance A (e.g., mixed objectives), and balance B. A costfield 422 includes a pillars field 432 and a speed field 434, aperformance field 424 includes a pillars field 436 and a speed field438, a reliability field 426 includes a pillars field 440 and a speedfield 442, a balance A field 428 includes a pillars field 444 and aspeed field 446, and a balance B field 430 includes a pillars field 448and a speed field 450. Each pillars field 432, 436, 440, 444, 448includes one or more pillar numbers of encoded data slices that are tobe transmitted from a corresponding transceiver of TR 1-5. Each speedfield 434, 438, 442, 446, 450 includes a relative speed indicator fortransmission of the one or more pillar numbers of encoded data slicesthat are to be transmitted from the corresponding transceiver of TR 1-5.

In a cost optimized example, TR module 1 transmits pillars 1-5 at anormal 1× relative wireless speed. Using one TR module may lower cost asdesired. In a performance optimized example, TR module 1 transmitspillar 1 at a 2× relative wireless speed, TR module 2 transmits pillar 2at 2×, TR module 3 transmits pillar 3 at 2×, TR module 4 transmitspillar 4 at 2×, and TR module 5 transmits pillar 5 at 2×. A performanceimprovement is provided by sending pillars 1-5 simultaneously viaparallel communications paths. In a reliability optimized example, TRmodules 1-5 transmit pillars 1-5 as in the performance optimized examplebut at a 1× speed.

In a balance A optimized example, TR modules 1-3 transmit pillars 1-3 atthe 1× relative wireless speed and TR module 4 transmits pillars 4-5 atthe 2× relative wireless speed. A balance is provided between cost andreliability by utilizing one less TR module but yet at a similarthroughput as the reliability optimized example. In a balance Boptimized example, TR module 1 transmits pillars 1-2 at a 4× speed, TRmodule 2 transmits pillars 3-4 at a 4× speed, and TR module 3 transmitspillar 5 at a 2× speed. Note that a balance is provided between cost andperformance by utilizing two fewer TR modules but yet at a similarthroughput as the performance example. Note that a decode thresholdnumber of encoded data slices are received at a 2× rate even when anyone of the TR modules is not operable.

FIG. 23 is a flowchart illustrating another example of acquiring acontent broadcast. The method begins with step 452 where a processingmodule (e.g., of a user device) acquires wireless signals from two ormore sites. The wireless signal acquisition may include one or more ofscanning, searching channels from a predetermined list, searchingchannels from a previous wireless cyclist, searching channels based onlocation, and searching all channels. The method continues at step 454where the processing module determines transmit wireless configurationof two or more sites based on one or more of receiving the transmitwireless configuration information from the two or more sites andanalyzing received information to extract transmit wirelessconfiguration information (e.g., pillar number assignment to wirelesspaths).

The method continues at step 456 where the processing module determinesreceive wireless configuration to enable receiving data slices ofdesired pillars based on one or more of a wireless quality levelindicator, an indicator of sites within range, an indicator of userdevices within range, and a pillar to wireless communications pathassignment indicator. The method continues at step 458 where theprocessing module configures wireless transceiver (TR) modules inaccordance with the receive wireless configuration by sending thereceive wireless configuration information to the TR modules associatedwith the processing module. The method continues at step 460 where theprocessing module receives encoded data slices via reception of wirelesssignals from transmitting TR modules of the two or more sites. Themethod continues at step 462 where the processing module decodes theencoded data slices from the two or more sites in accordance with anerror coding dispersal storage function to produce reconstructed datasegments.

The method continues at step 464 where the processing module determineswhether to reconfigure the receive wireless configuration. Thedetermination may be based on one or more of the wireless quality levelindicator, the indicator of sites within range, the indicator of userdevices within range, and the pillar to wireless communications pathassignment indicator. The method branches back to step 460 when theprocessing module determines not to reconfigure the receive wirelessconfiguration. The method loops back to step 452 when the processingmodule determines to reconfigure the receive wireless.

FIG. 24 is a flowchart illustrating another example of acquiring acontent broadcast, which includes similar steps to FIG. 23. The methodbegins with steps 452-462 of FIG. 23 where a processing module (e.g., ofa user device) acquires wireless signals from two or more sites,determines transmit wireless configuration of the two or more sites,determines a receive wireless configuration, configures transceiver (TR)wireless modules in accordance with the receive wireless configuration,receives encoded data slices via wireless communications from the two ormore sites, and reconstructs data segments utilizing data slices fromthe two or more sites. The method continues at step 478 where theprocessing module determines whether data reception performance is belowa performance threshold. The determination may be based on one or moreof a received data rate indicator, a received data error indicator, athreshold, a comparison of data reception performance to the threshold,a wireless quality level indicator, an indicator of sites within range,an indicator of user devices within range, and a pillar to wirelesscommunications path assignment indicator. The method repeats back tostep 460 of FIG. 23 when the processing module determines that the datareception performance is not below a threshold. The method continues tostep 480 when the processing module determines that the data receptionperformance is below a threshold.

The method continues at step 40 where the processing module acquireswireless signals from a sending user device transmitting copies of theencoded data slices. The wireless signal acquisition may be based onscanning wireless signals of the user device and/or sending a requestmessage to another user device to request that it relay the copies ofthe encode slices. The method continues at step 482 where the processingmodule determines transmit wireless configuration of one or more of thesending user device based on receiving information from the user deviceand/or by extracting information from one or more pillar communicationsand of the two or more sites.

The method continues at step 484 where the processing modulere-determines the receive wireless configuration based on the transmitwireless configuration of the sending user device and/or the transmitwireless configuration of the two or more sites. The processing modulemay determine to receive pillar communications from two or more sitesand another user device. The method continues at step 486 where theprocessing module configures a wireless TR modules associated with theprocessing module in accordance with the receive wireless configuration.The method continues at step 488 where the processing module receivesencoded data slices (e.g., including copies) via wireless from the twoor more sites and/or the sending user device.

The method continues at step 490 where the processing module decodes thereceived encoded data slices in accordance with an error codingdispersal storage function to produce reconstructed data segments. Themethod continues at step 492 where the processing module determineswhether to reconfigure the wireless based on the wireless performanceand/or the received data. The method repeats back to step 488 when theprocessing module determines not to reconfigure the wireless. The methodloops back to the step 480 when the processing module determines toreconfigure the wireless.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “operably coupled to”, “coupled to”, and/or “coupling” includesdirect coupling between items and/or indirect coupling between items viaan intervening item (e.g., an item includes, but is not limited to, acomponent, an element, a circuit, and/or a module) where, for indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.As may even further be used herein, the term “operable to” or “operablycoupled to” indicates that an item includes one or more of powerconnections, input(s), output(s), etc., to perform, when activated, oneor more its corresponding functions and may further include inferredcoupling to one or more other items. As may still further be usedherein, the term “associated with”, includes direct and/or indirectcoupling of separate items and/or one item being embedded within anotheritem. As may be used herein, the term “compares favorably”, indicatesthat a comparison between two or more items, signals, etc., provides adesired relationship. For example, when the desired relationship is thatsignal 1 has a greater magnitude than signal 2, a favorable comparisonmay be achieved when the magnitude of signal 1 is greater than that ofsignal 2 or when the magnitude of signal 2 is less than that of signal1.

While the transistors in the above described figure(s) is/are shown asfield effect transistors (FETs), as one of ordinary skill in the artwill appreciate, the transistors may be implemented using any type oftransistor structure including, but not limited to, bipolar, metal oxidesemiconductor field effect transistors (MOSFET), N-well transistors,P-well transistors, enhancement mode, depletion mode, and zero voltagethreshold (VT) transistors.

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described, at least in part, in terms ofone or more embodiments. An embodiment of the present invention is usedherein to illustrate the present invention, an aspect thereof, a featurethereof, a concept thereof, and/or an example thereof. A physicalembodiment of an apparatus, an article of manufacture, a machine, and/orof a process that embodies the present invention may include one or moreof the aspects, features, concepts, examples, etc. described withreference to one or more of the embodiments discussed herein.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention. One of average skill in the art will also recognize that thefunctional building blocks, and other illustrative blocks, modules andcomponents herein, can be implemented as illustrated or by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or any combination thereof.

What is claimed is:
 1. A method comprises: receiving a write requestregarding an encoded data slice at a distributed storage unit, whereinthe write request includes the encoded data slice and a value indicationin a slice length field, in which a first value for the value indicationindicates a write request to delete the encoded data slice from a memoryspace of the distributed storage unit and a second value for the valueindication indicates storing of the encoded data slice in thedistributed storage unit; determining, at the distributed storage unit,whether the write request contains the first value or the second valuefor the value indication; storing a deletion marker in a directory, whenthe write request pertains to deleting the encoded data slice;determining when to delete the encoded data slice based on a deletionscheme, when the write request pertains to deleting the encoded dataslice, deleting the encoded data slice and clearing the deletion markeronce the encoded data slice is deleted; and determining whether theencoded data slice is allowed to be stored, when the write requestpertains to storing the encoded data slice, and storing the encoded dataslice when storing is allowed.
 2. The method of claim 1, wherein thevalue indication is a number, a flag or a code.
 3. The method of claim1, wherein the deletion scheme for determining when to delete theencoded data slice comprises at least one of: deleting the encoded dataslice when memory availability compares unfavorably to a memoryavailability threshold; deleting the encoded data slice when apredetermined period of time has expired after receiving the writerequest; deleting the encoded data slice when utilization of the memoryspace compares unfavorably to a memory space usage threshold; anddeleting the encoded data slice based on a deletion instruction of thewrite request.
 4. The method of claim 1, wherein when the deletionscheme is not met, not deleting the encoded data slice.
 5. The method ofclaim 1, wherein when determining whether the encoded data slice isallowed to be stored, determining at least one of: indicating thatstoring the encoded data slice is allowable when the received encodeddata slice is associated with a directory file; indicating that storingthe encoded data slice is allowable when memory availability comparesfavorably to a memory availability threshold; and indicating thatstoring the encoded data slice is allowable when utilization of thememory space compares favorably to a memory space usage threshold. 6.The method of claim 1 further comprises: sending an error responsemessage in response to the write request, when the encoded data slice isnot allowed to be stored when the write request pertains to storing theencoded data slice.
 7. A distributed storage device comprises: aninterface; a memory; and a processing module operable to: receive, viathe interface, a write request regarding an encoded data slice, whereinthe write request includes the encoded data slice and a value indicationin a slice length field, in which a first value for the value indicationindicates a write request to delete the encoded data slice from a memoryspace associated with the memory of the distributed storage unit and asecond value for the value indication indicates storing of the encodeddata slice in the memory; determine whether the write request containsthe first value or the second value for the value indication; store adeletion marker in a directory, when the write request pertains todeleting the encoded data slice; determine when to delete the encodeddata slice based on a deletion scheme, when the write request pertainsto deleting the encoded data slice, delete the encoded data slice andclear the deletion marker once the encoded data slice is deleted; anddetermine whether the encoded data slice is allowed to be stored, whenthe write request pertains to storing the encoded data slice, and storethe encoded data slice when storing is allowed.
 8. The distributedstorage device of claim 7, wherein the value indication is a number, aflag or a code.
 9. The distributed storage device of claim 7, whereinthe deletion scheme determines when to delete the encoded data slice byat least one of: deleting the encoded data slice when memoryavailability compares unfavorably to a memory availability threshold;deleting the encoded data slice when a predetermined period of time hasexpired after receiving the write request; deleting the encoded dataslice when utilization of the memory space compares unfavorably to amemory space usage threshold; and deleting the encoded data slice basedon a deletion instruction of the write request.
 10. The distributedstorage device of claim 7, wherein the processing module does notexecute deletion of the encoded data slice when the deletion scheme isnot met.
 11. The distributed storage device of claim 7, wherein theprocessing module functions to determine whether the encoded data sliceis allowed to be stored by at least one of: indicating that storing theencoded data slice is allowable when the received encoded data slice isassociated with a directory file; indicating that storing the encodeddata slice is allowable when memory availability compares favorably to amemory availability threshold; and indicating that storing the encodeddata slice is allowable when utilization of the memory space comparesfavorably to a memory space usage threshold.
 12. The distributed storagedevice of claim 7, wherein the processing module further functions tosend, via the interface, an error response message in response to thewrite request, when the encoded data slice is not allowed to be storedwhen the write request pertains to storing the encoded data slice.